@bluebird It is not referring to a physical snake. Michael Heiser says in “The Unseen Realm”
You can find more here
https://discourse.biologos.org/t/michael-heiser-serpent-son-s-of-god-nephilim-watchers-and-genesis
And when did snakes lose the ability to speak? To think? To know what God had said?
Then you make the assumption that when the snake is cursed to “On your belly you will go” this means it originally had legs. But this is followed by “And dust you will eat”. We know snakes “smell” by using their tongue so it certainly appears they are eating dust but we know that they are not. So the author got the vestigial legs right but the snakes diet wrong? Better solution is to realize that a real snake is not in view here.
But the river existed in “mid-fourth to third millennium BC” which means it was have been known to the people writing Genesis. How is this surprising?