Now that’s done, I can join the wild speculation of the rest of the thread.
The big question for me is why that tree was there to begin with.
I see the story as an etiological myth explaining loss of innocence and (if it’s not too anachronistic) our existential “thrown-ness” in the world–that unlike every other creature, we seem unaware of our purpose and at odds with our surroundings and ourselves. (Remember the immediate consequences of the Fall: pain in working for food and in giving birth, things other animals seem to do easily.)
The “real-world” explanation for the tree is that some mechanism had to exist in the story to explain our transition from happy innocents to self-aware, suffering adults.
“In-story,” I think we can say that humans weren’t created to live in the Garden forever. We were created to till the earth, to cultivate it and care for it (Gen 2:5, 1:26-28, 2:15, 3:23). Eden, I think, was our nursery, to prepare us to encounter the rest of creation and to be truly “like God” in having dominion over it, caring for it, and shaping it.
But we weren’t ready. We were newly created, like children. We had to mature. And part of that was learning boundaries, learning slowly for ourselves good and evil. The tree was there for us to eat of when we were ready, and it was there to teach us obedience and through obedience right and wrong until we were ready.
But the plan backfired. We disobeyed, and like children who encountered violence and sex to early (or rather were taught them by a mischievous older brother, the snake) we grew up too fast. It suddenly no longer made sense to keep us in the nursery; we had seen all that the garden was meant to shelter us from. We were, for better or worse, cast out into the world, too mature and headstrong to be kept at home, but not experienced enough to find our way. And like a problem child grown to adulthood, we’ve been struggling and rebelling and fucking up ever since, unable to forgive ourselves or accept our father’s forgiveness and help.