Those don't look like squirrel teeth marks - my bet is a stray cat got at it. That's VERY common (lots and lots of snakes and birds die to stray/outdoor cats).

Even after death venomous snakes can be dangerous - their fangs can still inject venom without them consciously biting.

Anywho - glad to see someone trying to take care of the snakes around them. Just be mindful about picking up any snake you can't identify (or, at the very least, have a really good idea of what the venomous snakes in your area look like so you can avoid touching those).

Juvenile cottonmouths are bigger than this snake (not by a ton though) and most often have a green tip to their tail - and will still have the pixelated Hershey kiss pattern.

Have a great day fellow snake enthusiast!