It doesn't require knowledge of the fossil record to know about snakes. Presumably, snakes were a part of people's everyday lives.
I do think that parts of Genesis were pre-scientific attempts to explain the world.
In Genesis 1, the world is as seen by a scientifically naive person. The heavens (just another word for the sky at that time) was seen as a domed ceiling. It was seen as having a luminosity independent of the sun, hence "let there be light" came before the sun. The sun, moon, stars were seen as fixtures attached to that ceiling. It describes water above the ceiling, presumably to account for the rain.
Of course, with today's science we can see that this is all wrong. Somehow the biblical literalists manage to come up with highly non-literal readings of Genesis 1, so as to allow themselves to remain in denial of the obvious fact that what it says is nonsense.
The Adam and Eve story was similar to the Kipling "Just So" stories. It was fiction, intended to give a pseudo-explanation of why humans seem different from other animals.
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