> Lots of songs have, like, "forced" slang or even changes in pronunciation or syllable stress to meet the constraints of the lyrics.

I agree. I’d be wary of this as a beginner, but when you get more advanced, it becomes helpful in untangling your hearing from the isolated, intentionally clean and slowed-down setting of a class.

People don’t actually talk like that. Some slur their speech, others have a heavy accent, and others just place emphasis wherever they feel like it. Some kinds of music* work well for giving you an ear for the changes that matter (And even with all the changes, natives still are able to understand most music, so it is a skill to learn).

* I love me some guturals in my music, but it's probably not the best way to train your ear for every day conversation

Regarding the Cartoons totally, way easier to understand them because they speaking slow. I'm learning German right now the same way

> Instead, I would go with cartoons or children/preteen's shows first.

Just be careful. I was watching Dora en Francais, and whenever Monsieur Diego was talking, I was like, woah, I understand it now, but that's cause he was speaking english.