If you study myths, if you put in the time to read hundreds and hundreds of them, you get a feel for how they work. They function on several levels.
At base level they are simply good stories that kids enjoy that usually give some kind of reason why something in nature is the way it is.
On a social level, they are teaching stories. Whatever CORE VALUES a culture has, it will inevitably encode into these myths. Enculturation is not usually conscious or prosaic, but picked up via osmosis, and myth is one of the best tools. When Jews and Christians read about Adam and Eve, it is not primarily for the "history," even if theytake it literally, but for the lessons it teaches about the nature of G-d, of the universe, and of humanity.
These values are not consiously placed into the story -- they come unconsiously through the mind of the story teller and whatever inspires them. Thus, myth is almost never allegorical, as allegory is a conscious use of symbolism.
There is another deeper level to myth that most people get to, because they have't been exposed to enough myth. When you read enoug myth, you begin to notice that the same stories are told over and over, and the same characters keep popping up in different forms. Many thoughtful people have asked the question, How is it that diverse cultures around the globe, most that have never met each other, essentially tell the same stories? We don't really know the answer. But we acknowledge that there is a part of our subconsious minds where these ideas are encoded, and we are simply born with the knowledge. These kinds of things are usually refered to as "Archetypal." In our age, they are the subject of a lot of thought by such great minds as Carl Jung and Joseph Campbell. One theory is that there is a kind of racial memory going on. But we just don't have a lot of hard core science to back it up.
But anyhow, that's where I was coming from earlier in the thread when I made the suggestion that the story of Adam and Chava could be a racial memory of the evolution of our moral sentience, and how this development alienated us from nature, from ourselves, from each other, and even from our Creator.
You know, if you are ever interested, you might find it fun to explore Jewish interpretations. They're pretty different from the Christian one, and there are a lot more ideas being thrown around. You can find plenty of Rabbis who will say that it was always part of G-d's plan that they eat of the tree, since G-d's desire was to create morally responsible beings. And the original "Adam" is considered to be androgenous, or hermaphroditic; when G-d "created Chava" he took Adam and divided him/her into the two sexes. I think all this stuff is pretty interesting, but not everyone does, so I hope I'm not boring you to tears.