Hi Smiddy 3,
Justin Martyr is the earliest who equated Snake with Satan and he was born in 100 CE.
The apocryphal Apocalypse of Moses is dated by some to as early his time, with some dating it as late as 300 CE.
The Eden story is religious fiction, written for religious political purposes. Not unique. Researching the subject tells us about the people at the time, and it warns us how we should respond to people who promote such material and thinking. Supernatural superstition for the superstitious.