What does genesis 3 teach us about human nature?

Leon R. Kass (The Beginning of Wisdom) says that the Garden of Eden is a purely mythic place. Man was never put in the Garden of Eden, because the garden never really existed. Kass says we can learn most from the story by regarding it as a mythical yet realistic portrait of permanent truths about our humanity, rather than as a historical yet idealised portrait of a blissful paradise we once enjoyed but lost. Kass believes that the audience for whom the story was written knew that it was not literally true, but learnt these moral truths by listening to the story.

It especially shows ours longing to be like the gods and our longing for immortality. We see this in Genesis 3:22, after Adam ate the fruit of the Tree of the Knowledge of Good and Evil and God said, "now the man is become like one of us." Adam had become like the gods, except that he was still mortal. So that he would not now eat of the Tree of Life and thus become immortal, God sent Adam and Eve from the Garden of Eden and placed cherubim and a flaming sWord to keep (block) the path to the Tree of Life (3:24).