The serpent has appeared in a huge array of documented mythologies throughout history, further back than even Ancient Egypt's god(s) Ra and Atum. The positioning of the serpent as somehow devious or threatening to the established order was by no means installed in Genesis.

Lynne A. Isbell, in her book The Fruit, The Tree, The Serpent, posits that the prevailing image of the serpent as harmful has its origins in our shared biology as primates. As we evolved into bipedal hunter-gatherers, she argues, serpents acted as our primary predator and may have even guided our evolutionary path to some extent. It therefore seems natural that human cultures have positioned serpents in this way throughout recorded history.

Regarding the snake as 'manipulative', the regular shedding of skin makes for an easy allusion to deception and deceit.