I wrote a book and put this thought in it...
Adam would not die unless he sinned. Death came by sin. Nothing could die before Adam and Eve's sin, since
Romans 5 teaches that sin came by ONE MAN.
Rom 5:12 KJV Wherefore, as
by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
We cannot circumvent that passage.
The fruit of Life was only said to restore everlasting life after death came into the fray when Adam sinned.
Gen 3:22 KJV And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever:
He would not have died before his sin, anyway. So the only conclusion for reading that God would mention the fruit of life would render Adam to never die must be that God had the remedy for the sin in the fruit BEFORE sin came into the human race. The Lord was slain from the foundation of the world! FOREKNOWLEDGE.
And yet GOD BARS MAN from the tree, while it had the ability to make him live forever after he sinned. Why? Why bar man from the remedy? The remedy would only render him immortal. But there had to be a death in order for man to be redeemed and sinless again. And of course this was to happen through Christ's death.
Had man been rendered immortal with sin in his life, there would be no chance for his salvation, since salvation occurs through the death of Christ identifying with our need to die due to sin.
So in reality, God was protecting man by barring him from the fruit of life after man sinned. Had man eaten of the fruit with sin still in his life, and no remission of sin, man would remain away from God forever with no hope of recovery. We know now that the plan of salvation for man was identification with Christ's death. But unless man could die, himself, the death of Christ could not STAND FOR man's death. Man had to be susceptible to death in order for Christ to vicariously die as man, and redeem him. So God barred man from the fruit of life after man's sin.
The fruit of life is now in the form of Christ, who hung on a tree, for us to spiritually eat his broken flesh and shed blood (indications of HIS DEATH) for us to have eternal life!
The only death outside the Garden would have been spiritual death in the devil. We read of the serpent possessed by the devil.
Gen 3:1 KJV Now the serpent was more subtil than any beast of the field which the LORD God had made. And he said unto the woman, Yea, hath God said, Ye shall not eat of every tree of the garden?
Rev 12:9 KJV And the great dragon was cast out, that old (OF ANCIENT TIMES) serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.