Why a snake?

The next question I ask of Genesis Two: why a serpent in particular.

Many other animals have enjoyed a reputation for dangerous cunning, in the long tradition of Old World human animism. The jackal; the hyena. The owl. The bear to an extent. Certainly the ferret. The crocodile, the scorpion. But Genesis Two went with the snake.

I'd look at Near Eastern post-animism, first. The Epic of Gilgamesh brought in a motif, of a snake eating the flower of immortality. That the snake speaks to Eve first, hints at a sexual subtext.

Fertility actually pervades Genesis Two. Woman is created at the start; at the end, woman is doomed to bear children, which she did not in Eden.

The "knowledge of good and evil" which the serpent brought was, exactly, the Neolithic Revolution. Man and women learnt agriculture and animal-domestication. (Perhaps excepting the dog.)