I personally always thought Adam and Eve weren’t real people, but were figurative for the whole of humanity. However, in recent years I have run into some ideas that, while ridiculous in themselves, got me to thinking.
What if at some point in history God took proto-humans (such as cave men), and altered them in some way (His own Way, if you will), thus creating the first homo sapiens we are today? In fact, these humans wouldn’t be ‘just like us’, they would have been more than us. Remember, He made them perfect in every way, physically, mentally, and spiritually. Even after these people “fell”, they probably didn’t lose all their “specialness”, heightened abilities which would have made them seem “godlike” to those proto-humans who weren’t altered. So maybe Cain, when he went off, married one of these proto-humans. So maybe it was just two people–Adam and Eve–who started it all. And as the children of Adam and Eve intermarried with proto-humanity,
much of their genetic contribution to the newly coming humanity (us) was still diluted by the proto-human contribution. And by the time the Great Flood happened (and I believe there is enough evidence in the fossil records to confirm it did happen), the survivors were already much “less” (so to speak) than their common ancestors, Adam and Eve. Heck, since this appears to be in that time period, maybe it was these people who built the first pyramids, and the Natzca lines, and so forth. (There still seems to be so much debate about these ancient wonders; no one really seems to be able to say definitively who built the most ancient of them.) Anyway, that’s my two cents (allright, given how much I wrote, it was a buck and a quarter).