Adam and Eve were created with an innocent nature.
God put the tree of the knowledge of good and evil in the garden for He gave them a choice.
But they could eat from the tree of life because they were innocent.
Since they were created innocent it would of never entered their mind to eat from the forbidden tree, and they would of never wanted to do it nor could they for they did not have that capability to sin.
The only way they could sin is if an outside source tempted them with an alternate reality and since God gave them a choice He allowed Satan to tempt Eve which she said they cannot eat of the tree for that is all she could think and know.
Then Satan tempted her with an alternate reality that if she ate from the tree she would be as a god an elevated position, and possibly that God could not touch her in her elevated position to be like a god.
Eve ate from the tree and sinned, and then Eve was the outside source that tempted Adam by showing him she did not die and nothing happened to her, and possibly told her that he would be elevated as a god, and Adam ate and sinned.
Then God ousted them from the garden and protected the tree of life for if they ate from the tree in their sinful position then they would stay that way and there would be no reversal, and they could not be saved and their offspring could not be saved.