Although I believe Adam and Eve existed, I think the story of the Garden of Eden, the Tree of Life and Tree of Knowledge, is one big allegory, to show the relationship of mankind to God.
Garden of Eden = Premortal life with God
Naked = pure and innocent before God
Tree of Life = Living forever in the presence of God's love
Tree of Knowledge = Earth Life (mortality)
All of us (mankind) could choose to come to earth (mortality), and in so doing we would be cut off from God's immediate presence, and be subject to mortal struggles. We would die, but we also can know the joy of having children, etc.
And, we were given a way back (through Christ)