Apparently African American Vernacular English (said AAVE, pronouncing each letter) is just a dialect and there’s a couple other that fit under just AAE? I never knew about any of those beside AAVE.
Seems to be proper name for the kind of language a stereotypical black character in a movie would use. Can’t say about real world, since I don’t live in the USA.
AAVE is the “relaxed” English you’re talking about. And with the interconnectedness of the Internet, AAVE is kind of displacing the rest.
But honestly from an etymological standpoint I think it makes sense to view AAVE as the base and then just having other flavors of it. From that link they’re trying to break it down I to multiple distinct groups.