The serpent was inside Eve.
It's that thought process that a person goes through when they consider sinning vs. not sinning, and convince themselves that "it won't hurt anything"
Scapegoating.
Excusing one's self from responsibility.
Blaming one's transgressions on a literal snake or external Satan, instead of taking accountability.
The sin of Judah.
Same thing Judah did when he reasoned that selling Joseph into slavery would somehow free Judah and his brothers from being guilty of the sin of killing Joseph. He reasoned, "well, he's in that pit, he's gonna die anyway now, I can't get my brothers to change their mind, but if I can get them to sell him to somebody else, we'll get a little money and the slavers will be the ones that are responsible for killing him or whatever happens, not us."
Same thing Judas did when he reasoned that the pharisees were so determined to get Jesus, it was just a matter of time anyway, Judas might as well make a little money off of it, and since they're the ones that are actually going to do the killing, Judas "won't be guilty."
The serpent is us on the inside when we excuse our sin before we do it.
Satan is the part of our self that we hate and wish we could cast out. Our adversary. And God is going to cast Him out.
All of the physical stories teach us something about our selves. All the characters are ways we think and behave.
We can never make heads or tails of a literal talking snake. But to keep the one inside us in check, will change hearts.
Repentance and brotherly love, not biblical wisdom, for the win.
The bible says making perfume that smells like dead insects is more valuable than mixing folly with wisdom, like blaming our sin on Eve and a demon possessed talking snake. Folly.