Is there such a thing as free standard standalone character armatures? I would like to start building an animation library using the widest, most generic, most flexible armature possible. I know nothing about character rigging best practices at all. I just want to take a rig that conforms to some sort of recognized standard, and then just start making animations for the library.

Is there such a thing? Or is there no standardization at all between character armatures? I've tried googling for information, but literally all I can find is 3D models that some other person created and that have a rig attached, with no information that I feel I can usefully trust.

Thank you for your time?
The Rigify addon includes a basic armature that sounds like what you might be looking for.