its not only man that is meant for immortality:
The Wisdom of Solomon 1:13 For God made not death: neither hath he pleasure in the destruction of the living. 14 For he created all things, that they might have their being: and the generations of the world were healthful; and there is no poison of destruction in them, nor the kingdom of death upon the earth:
And the animals are named wild beasts [qhria], from their being hunted [qhreuesqai], not as if they had been made evil or venomous from the first–for nothing was made evil by God, but all things good, yea, very good,–but the sin in which man was concerned brought evil upon them. For when man transgressed, they also transgressed with him . . . so in like manner it came to pass, that in the case of man’s sin, he being master, all that was subject to him sinned with him. When, therefore, man again shall have made his way back to his natural condition, and no longer does evil, those also shall be restored to their original gentleness. Theophilus to Autolycus Book II.XVII
God did not, as some people think, just give Paradise to our ancestor at the beginning, nor did He make only Paradise incorruptible. No! Instead, He did much more . . . Neither Eve nor Paradise were yet created, but the whole world had been brought into being by God as one thing, as a kind of paradise, at once incorruptible yet material and perceptible. It was this world, as we said, which was given to Adam and to his descendants for their enjoyment. Does this seem strange to you? It should not. St. Symeon the New Theologian, Ethical Discourses 1.1, in On the Mystical Life, vol. 1, p. 21
[God] wills to hold it [Paradise] out to us as a type of the indissoluble life to come, an icon of the eternal Kingdom of Heaven. If this were not the case, then the Garden, too, would have had to be cursed, since it was the scene of the transgression. However, God does not do this, but instead curses the whole rest of the earth which, as we have said, was incorruptible just like Paradise, and produced fruit of its own accord. St. Symeon, Ethical Discourses 1.2
Doubtless indeed vultures did not look around the earth when living things came to be. For nothing yet died of these things given meaning or brought into being by God, so that vultures might eat it. Nature was not divided, for it was in its prime; nor did hunters kill, for that not yet the custom of human beings; nor did wild beasts claw their prey, for they were not yet carnivores. And it is customary for vultures to feed on corpses, but since there were not yet corpses, nor yet their stench, so there was not yet such food for vultures. But all followed the diet of swans and all grazed the meadows. St. Basil the Great, On the Origin of Humanity 2.6
‘Let the Church neglect nothing; everything is a law. God did not say: “I have given you the fishes for food, I have given you the cattle, the reptiles, the quadrupeds.” It is not for this that He created, says the Scripture. In fact, the first legislation allowed the use of fruits, for we were still judged worthy of Paradise.
‘What is the mystery which is concealed for you under this?
‘To you, to the wild animals and the birds, says the Scripture, fruits, vegetation and herbs (are given) … We see, however, many wild animals which do not eat fruits. what fruit does the panther accept to nourish itself? What fruit can the lion satisfy himself with?
‘Nevertheless, these beings, submitting to the law of natures, were nourished by fruits. But when man changed his way of life and departed from the limit which had been assigned him, the Lord, after the Flood, knowing that men were wasteful, allowed them the use of all foods; “eat all that in the same was as edible plants” (Gen. 9:3). By this allowance, the other animals also received the liberty to eat them.
‘Since then the lion is a carnivore, since then also vultures watch for carrion. For the vultures were not yet looking over the earth at the very moment when the animals were born; in fact, nothing of what had received designation or existence had yet died so that the vultures might eat them. Nature had not yet divided, for it was all in its freshness: hunters did not capture, for such was not yet the practice of men; the beasts, for their part, did not yet tear their prey, for they were not carnivores … But all followed the way of the swans, and all grazed on the grass of the meadow …
‘Such was the first creation, and such will be the restoration after this. Man will return to his ancient constitution in rejecting malice, a life weighed down with cares, the slavery of the soul with regard to daily worries. When he has renounced all this, he will return to that paradisal life which was not enslaved to the passions of the flesh, which is free, the life of closeness to God, a partaker of the life of the angels.’ St. Basil the Great, On the Origin of Man, 2:6-7
The earth, created, adorned, blessed by God, did not have any deficiencies. It was overflowing with refinement. “God saw,” after the completion of the whole creation of the world, “everything that He had made: and, behold, it was very good.” (Gen. 1:31).
Now the earth is presented to our eyes in a completely different look. We do not know her condition in holy virginity; we know her in the condition of corruption and accursedness, we know her already sentenced to burning; she was created for eternity. . . . Plants were not subjected either to decay or to diseases; both decay and diseases and the weeds themselves, appeared after the alteration of the earth following the fall of man . . . According to its creation, there was on it only the splendid, only the wholesome, there was only that which was suitable for the immortal and blessed life of its inhabitants . . . The beasts and other animals lived in perfect harmony among themselves, nourishing themselves on plant life. St. Ignatius Brianchaninov, Homily on Man
The beautiful things of this world are only hints of that beauty with which the first-created world was filled, as Adam and Eve saw it. That beauty was destroyed by the sin of the first people . . . Thus also did the fall into sin of the first people destroy the beauty of God’s world, and there remain to us only fragments of it by which we may judge concerning the primordial beauty. St. Barsanuphius of Optina, Elder Barsanuphius of Optina, pg. 468
In not wishing to be nourished by Him [God], the first man rightly fell away from the Divine life, and took death as another parent. Accordingly he put on himself the irrational form, and blackened the inconceivable beauty of the Divine, and delivered over the whole of nature as food for death. Death is living on this through the whole of this temporal period, making us his food. St. Maximus, Ambiguum 10.
What I am saying is that in the beginning sin seduced Adam and persuaded him to transgress God’s commandment, whereby sin gave rise to pleasure and, by means of this pleasure, nailed itself in Adam to the very depths of our nature, thus condemning our whole human nature to death and, via humanity, pressing the nature of (all) created beings toward mortal extinction. St. Maximus, Ad Thalassium 6.1
The creation of all things is due to God, but corruption came in afterwards due to our wickedness and as a punishment and a help. “For God did not make death, neither does He take delight in the destruction of living things” (Wisdom 1:13). But death is the work rather of man, that is, its origin is in Adam’s transgression, in like manner as all other punishments. St. John of Damascus, Exact Exposition 2.28
Commenting on Romans 8:20: What is the meaning of “the creation was made subject to futility”? That it became corruptible. For what cause, and on what account? On account of you, O man. For since you took a body mortal and subject to suffering, so also the earth received a curse, and brought forth thorns and thistles. St. John Chrysostom, Homilies on Romans, 14.
He [the Apostle Paul] discourses concerning creation’s bondage, an shows for whose sake such a thing has occurred — and he places the blame on us. What then? In suffering these things on account of another, has creation been maltreated? By no means, for it has come into being for my sake. So then, how could that which has come into being for my sake be unjustly treated in suffering those things for my correction? St. John Chrysostom, Homilies on Romans, 14
What armed death against the cosmos? The fact that one man tasted of the tree only. St. John Chrysostom, Homilies on Romans, 10.
It is said that when the world was first created it was not subject to flux and corruption. According to Scripture it was only later corrupted and “made subject to futility” — that is, to man — not by its own choice but by the will of Him to whom it is subject, the expectation being that Adam, who had fallen into corruption, would be restored to his original state. St. Gregory of Sinai, On Commandments and Doctrines 11
St. Innocent of Alaska, Indication of the Way into the Kingdom of Heaven, http://www.orthodox-christianity.com/2013/02/on-the-fall-of-man-2/
God, having created Adam in His image and likeness, endowed him with many of His qualities. The most important of these was immortality. God, being all-just, created Adam sinless and pure. Being all-blessed, He created Adam blessed also, and this blessedness or beatitude was meant to increase in him day by day. As the book of Genesis states, Adam lived in the most beautiful garden (named Eden or Paradise), planted by God, and there he enjoyed all the blessings of life. He knew no sickness nor suffering. He feared nothing, and all beasts submitted to him as their master.
… The whole of nature, which had previously served Adam as a means to happiness, had now become hostile to him. From then on Adam and all his descendants began to suffer from cold and heat and to experience hunger and the effect of changes in climate and environmental conditions. Animals became unfriendly toward people and looked upon them as enemy or prey. Adam’s descendants began to suffer from different diseases, which gradually became more varied and severe. Men forgot that they were brothers and began to fight with each other, to hate, to deceive, to attack and to kill each other. And finally, after all kinds of hard labors and tribulations, they were doomed to die, and, as sinners, to go to Hades and experience eternal punishment there.
Inasmuch, therefore, as the opinions of certain [orthodox persons] are derived from heretical discourses, they are both ignorant of God’s dispensations, and of the mystery of the resurrection of the just, and of the [earthly] kingdom which is the commencement of incorruption, by means of which kingdom those who shall be worthy are accustomed gradually to partake of the divine nature . . . It is fitting, therefore, that the creation itself, being restored to its primeval condition, should without restraint be under the dominion of the righteous; and the apostle has made this plain in the Epistle to the Romans, when he thus speaks: “For the expectation of the creature waiteth for the manifestation of the sons of God. For the creature has been subjected to vanity, not willingly, but by reason of him who hath subjected the same in hope; since the creature itself shall also be delivered from the bondage of corruption into the glorious liberty of the sons of God.” St. Irenaeus, Against Heresies 5.32.1
For the creation was made subject to futility, [St. Paul] says, and he expects that it will be set free from such servitude, as he intends to call this world by the name of creation. For it is not what is unseen [the angelic world] but what is seen that is subject to corruption. The creation, then, after being restored to a better and more seemly state, remains, rejoicing and exulting over the children of God at the resurrection; for whose sake it now groans and travails, waiting itself also for our redemption from the corruption of the body, that, when when we have risen and shaken off the mortality of the flesh . . . and have been set free from sin, it also shall be freed from corruption and be subject no longer to futility, but to righteousness. St. Methodios of Olympus and Patara, Discourse on the Resurrection, ANF, vol. 6, p. 366
The fate of visible nature has, from the beginning of its existence, been under the power of the influence of man . . . Organically and mystically connected with man as with a God-like creature of God, nature in the essence of its life depends upon man and always moves strictly commensurately with man. When man chose the path of sin and death as his path through history, all of nature, as the results of its inner dependency on man, followed after him. The fall of man was at the same time the fall of nature, and the curse of man became the curse of nature. And from that time man and nature, like two inseparable twins, blinded by one and the same darkness, deadened by one and the same death, burdened by one and the same curse, go hand in hand through history, through the abysmal wilderness of sin and evil. Together they stumble, together they fall, and together they arise, ceaselessly striving toward the distant conclusion of their sorrowful history. St. Justin Popovich, The Orthodox Philosophy of Truth: The Dogmatics of the Orthodox Church vol. 3 p. 792
Adam was placed as lord and king of all the creatures . . . And so, when he was taken captive, the creation which ministered to and served him was taken captive together with him. For through him death came to reign over every soul. St. Macarius the Great, Homilies 11.5
“Death is not natural; rather it is unnatural. And death is not from nature; rather it is against nature. All of nature in horror cries out: “I do not know death! I do not wish death! I am afraid of death! I strive against death!” Death is an uninvited stranger in nature . . . Even when one hundred philosophers declare that “death is natural!” all of nature trembles in indignation and shouts: ” No! I have no use for death! It is an uninvited stranger!” And the voice of nature is not sophistry. The protest of nature against death outweighs all excuses thought up to justify death. And if there is something that nature struggles to express in its untouched harmony, doing so without exception in a unison of voices, then it is a protest against death. It is its unanimous, frantic, and heaven-shaking elegy of death. St. Nikolai Velimirovich, Selected Writings
Paradise, even heaven itself, is accessible to man; and the creation, both of the world and above the world, which long ago was set at variance with itself, is fit together in friendship; and we men are made to join in the angels’ song, offering the worship of their praise to God. St. Gregory of Nyssa, A Sermon for the Feast of the Lights
For that all the creation is in bondage the great Paul declares,— he who in the schools above the heavens was instructed in that knowledge which may not be spoken, learning these things in that place where every voice that conveys meaning by verbal utterance is still, and where unspoken meditation becomes the word of instruction, teaching to the purified heart by means of the silent illumination of the thoughts those truths which transcend speech. St. Gregory of Nyssa, Against Eunomius 3.1
Look at the total result: how fruitful was the Word! God issued His fiat, and it was done: God also saw that it was good; not as if He were ignorant of the good until He saw it; but because it was good, He therefore saw it, and honoured it, and set His seal upon it; and consummated the goodness of His works by His vouchsafing to them that contemplation. Thus God blessed what He made good, in order that He might commend Himself to you as whole and perfect, good both in word and act. As yet the Word knew no malediction, because He was a stranger to malefaction. We shall see what reasons required this also of God. Meanwhile the world consisted of all things good, plainly foreshowing how much good was preparing for him for whom all this was provided. Who indeed was so worthy of dwelling amongst the works of God, as he who was His own image and likeness? Tertullian, Against Marcion 2.4
As long as Adam loved God and observed His commandment, he dwelt in the Paradise of God and God abode in the paradisiacal heart of Adam. Naked Adam was clothed with the grace of God and, surrounded by the animals, he held and caressed them lovingly, and they, in turn, licked him devoutly, as their Master. When Adam violated God’s commandment., he was stripped of the grace of God, clothed with a garment of skin and exiled from Paradise. Grace-filled Adam became wild, and many animals, because of Adam, were also made savage, and instead of approaching him with devoutness and licking him with love, they lashed out at him with rage in order to tear at or bite him. Elder Paisios, Epistles, pg. 203-204
Behold the life of innocent Adam in Eden, the lordship of man over creation, which together with us groans because of our fall and thirsts to be delivered into the “liberty of the children of God” (Rom. 8:21). The Life of St. Paul of Obnora, in the Northern Thebaid
St. Paul claims that death is the enemy  which came into the world and passed unto all men through the sin of one man. not only many, but all of creation became subject to corruption. The subjugation of man and creation to the power of the devil and death was obviously a temporary frustration of the original destiny of man and creation. It is false to read into Paul’s statements about the first and second Adams the idea that Adam would have died even though he had not sinned, simply because the first Adam was made eis psychen zosan—which expression, according to St. Paul’s usage within the context, clearly means mortal. Adam could very well have been created not naturally immortal, but if he had not sinned there is no reason to believe that he would not have become immortal by nature. This is certainly implied by the extraordinary powers St. Paul attributes to death and corruption. Fr. John Romanides, Original Sin According to St. Paul, http://www.orthodoxinfo.com/inquirers/frjr_sin.aspx#127
The Ancestral Sin, p. 41-42
When philosophical systems try to explain the phenomena of things and the presence of evil in them on the basis of what is known about nature, it is absolutely natural for them to confuse the idea of the creation of mater with its fall. If we begin with philosophical and scientific observations of the material world, it is logically impossible to arrive at a distinction between the creation of the world and its fall. Quite simply, this is because the reality before our eyes presents nature as it is now, after the fall … Philosophy is unable to bridge [its] dualism between matter and reality because it is impossible for natural man to distinguish between the wholly positive creation of the world and the fall of the world. Man cannot know this division except by revelation.
The dualism of matter and reality is largely based on the idea that death is both a natural and phenomenal fact since matter and the material world in general are without permanent reality, something that belongs to a different dimension. In contrast to the philosophical method, through the divine revelation given to the Prophets, the special people of God learned to distinguish clearly between the world’s creation and the world’s fall, as well as between the present age, which is under the sway of the devil and death, and the future age of the resurrection and the incorruptibility of matter.
7.4. Now, if there were merely a misdemeanour in question, and not a consequent corruption, repentance were well enough. But if, when transgression had once gained a start, men became involved in that corruption which was their nature, and were deprived of the grace which they had, being in the image of God, what further step was needed? or what was required for such grace and such recall, but the Word of God, which had also at the beginning made everything out of nought? 5. For His it was once more both to bring the corruptible to incorruption, and to maintain intact the just claim of the Father upon all. For being Word of the Father, and above all, He alone of natural fitness was both able to recreate everything, and worthy to suffer on behalf of all and to be ambassador for all with the Father. St. Athanasius, On the Incarnation
… Fr. Andrew Louth says that St. Athanasius sees the fall as cosmic in Maximus the Confessor, pg. 64: “ Even St. Athanasius, a Christian thinker of relatively unsophisticated philosophical culture, interprets the Fall in terms of corruption and death, seen as affecting the whole cosmic order.”
Fr. Dumitru Staniloae, The Experience of God: Orthodox Dogmatic Theology: Vol. 2: The World: Creation and Deification, pg. 1,
The economy of God, that is, his plan with regard to the world, consists in the deification of the created world, something which, as a consequence of sin, implies also its salvation. The salvation and the deification of the world presuppose, as primal divine act, its creation. Salvation and deification undoubtedly have humanity directly as their aim but not a humanity separated from nature, rather one that is ontologically united with it. For nature depends on man or makes him whole, and man cannot reach perfection if he does not reflect nature and is not at work upon it. Thus by ‘world” both nature and humanity are understood; or when the word “world” is used to indicate one of these realities, the other is always implied as well.
Fr. Nikita Grigoriev, Faith and Delusion, p. 9-10
Here it is absolutely and vitally important to understand that everything which God created in the beginning was perfectly good. Everything was indescribably magnificent and good without even the slightest hint of evil, harm, grief or insufficiency, and certainly not death. God created everything in brilliant perfection. In that primordial world there was no illness, no fear, no danger. The animals did not fear or devour one another for they were given grass for forage, and man was given grain and fruits. God created man for life, not for death. God did not create death and in the primordial world there was no death. Even fruits did not perish and upon falling from a tree immediately metabolized into fragrant earth. Not only was man not threatened by death or illness, but even did not burn him and water did not drown him; all the animals and nature recognized him as their king and master and served and submitted to him in love and harmony.
All that man had to do was to grow and develop spiritually. Man, created in the image of God faced an unimaginably joyous future, infinitely perfecting himself in his God-likeness.
St. Philaret of Moscow, Commentary on the Book of Genesis, p. 42
Since God has approved of the whole kingdom of plants (cf. Gen. 1:12), man should not rebel against Him, seeing that some plants are poisonous or noxious. If the fall of man had not subjected the entire earth to corruption, we would find in them only good and useful properties.
St. Epiphanius of Salamis, Panarion 52.2, trans. Frank Williams, vol. 2, p. 69
Adam and Eve had the purest air, temperately dispensed to them by God with all mildness, neither sharpened by the rigor of cold, not enervated by the extremely unpleasant heat of summer. The land had been designed as an immortal abode very well made by God; it was filled with gladness and well-being, and as I said, got neither hot nor cold.
Venerable Bede, Commentary on Genesis 1:29-30, ACW, p. 131
On the Creation of Adam and Eve, http://www.orthodox-christianity.com/2011/11/venerable-bede-on-the-creation-of-adam-and-eve/comment-page-1/#comment-887
Therefore Adam, the new man, was created from earth after God, so that he was just, holy, and true, subject to and humbly dependent upon the grace of his Creator, who is eternally and perfectly just, holy, and true. And since he corrupted this most beautiful newness of the divine image in himself by sinning, and engendered the corrupt family of the human race from himself, there came the second Adam, that is, the Lord himself and our Creator, born from the Virgin, created imperishably and without change in the image of God, free of all fault and full of all grace and truth, in order to restore his image and likeness in us by his example and gifts … But perhaps it could be said that God foreknew that man would sin, and by sinning that he, whom God created immortal, would become mortal … Adam was certainly created immortal, in the sense that he could not die if he did not sin; but if he sinned, he would die.
On the Creation of Adam and Eve
It is proper to ask for what profit man received dominion over fish and birds and all the living creatures of the earth, and for what uses or comforts these were created for man, if he never sinned, since the sequel of this passage declares that in the first creation they were not granted to him for food but only the green plants and the fruits of the trees … Since it is plainly said that every plant and all trees were given to men and to birds and to all the living creatures of the earth for food, it is clear that those birds did not live by stealing the food of weaker animals, nor did the wolf search out an ambush around the sheepfold, nor was the dust the serpent’s food, but all things in harmony fed upon the green plants and the fruits of the trees.
— Archimandrite Ephraim of Vatopaidi, Creation and the End of Ages, http://www.johnsanidopoulos.com/2011/12/creation-and-end-of-ages.html
The fall of man, who was the ‘crown of creation’, has caused the fall of the entire creation which “has been groaning together in the pains of childbirth” (Romans 8″22). This explains the main teaching of our Church, which views the creation as a whole, which is being guided towards perfection and deification; man and nature together. Man and nature are not distinct in the design of the creation. Therefore man has a duty to maintain a good relationship with the rest of the creation. The fact that man remains in the fallen condition perilously prolongs the world enduring in the same condition. Thus man contributes to the perversion and degradation of nature. Therefore, the fall has not only distorted man existentially and morally but also his very same environment.
…In His Second Coming, Christ will not only restore human nature but the entire creation. Since the rest of the creation fell because of man, it will be regenerated by the sanctified man. When man attains sanctification, his surrounding environment is also sanctified. We find many such examples in the lives of the saints. A lion was attending the needs of St Gerasimos of Jordan; St Seraphim of Sarov was feeding a bear as if it was a tame lamb; Elder Paisios the Hagiorite was known to be keeping company with snakes and other wild animals.
Along with the resurrection and regeneration of man, nature will also be absolved of corruption. According to St Symeon the New Theologian, nature will become non-material and eternal. “During the regeneration, nature will become a non-material abode, beyond human perception” (St Symeon The New Theologian: Moral Issues, 1, 5).
Met. Hierotheos Vlachos, Life After Death, p. 318
It is a clear teaching of the Church that the creation is the work of God, that it was corrupted through the fall of man and that it will also be freed from this corruption
[writing on Rom. 8:19-22] … Secondly, creation was subjected to corruption, not of its own will, since creation has no will or freedom, but because of the fall of man. Man swept the whole of creation into corruption. Thirdly, creation groans and travails with man and yearns and hopes for liberation. Fourthly, the earnest expectation of it refers to the revelation of the sons of God. In so far as man was the cause of its fall, its renewal should come by man.
Canon for Afterfeast of Theophany, Jan. 11, Ode 3
He who once assumed the guise of a malignant serpent and planted death in the garden of creation, is now cast into darkness by Christ’s coming in the flesh, and by assailing the Master, the Dawn which hath shone forth upon us, he crusheth his own loathsome head.