Git still supports password authentication, as well as many other protocols. GitHub chose to restrict which protocols and authentication schemes are allowed on its platform.

But obviously, learning about the tools you are using is always a good idea.

My preferred "tutorial" is this one: https://codewords.recurse.com/issues/two/git-from-the-inside...

It is more advanced than the usual introductions but it demystifies most of the git concepts.