Super simple Auth0 usage with NO JS framework?

Question

New to Auth0, so please forgive my ignorance.

After spending hours going through examples and docs for Auth0, I feel like I know less about it now than when I started. I'm not using any of the frameworks pointed to by the example/docs. I just want Auth0 to manage the user id/password login part of the site, and when a user signs in, return a unique id that I can match up to the user's data in a table.

Everything I'm seeing seems a lot more complicated that I would have guessed it could be.

Is there a way to pass the user id and password to a function in Javascript that returns a result code and unique id for a user when they sign-in? I presume that if I have a form with user id and password field and a button, I would use AJAX or something to send the sign in info, then await the response. That would indicate if the sign-in was valid, and provide a unique id (or use the passed user id to locate the user's info?)

Is there a very simple example I can take a look at to see how it's done?

Also, a lot of the terms used with Auth0 are unclear as to what they are used for, or where I would get the info to fill them out. Is there a glossary available?

Thanks!