What's a good Android app for just playing my MP3s in the background while I'm grading papers or prepping for class? I don't need any fancy streaming services, just something simple.

Okay, so I was looking for something to play my old MP3s – you know, the ones I ripped from CDs back in the day. My students, bless their hearts, recommended 'Music Player & MP3 Music.' Took me a few days to figure out all the features, but it's surprisingly intuitive once you get the hang of it. I can create playlists for different moods – classical for grading, some classic rock for when I'm planning my history lessons. It runs in the background, which is key, so I can still use my other apps. It's like having a teaching assistant in your pocket, but instead of grading papers, it's playing my tunes. Why do they hide the settings button there, though? Honestly, sometimes I think these developers are messing with us older folks on purpose. But overall, it does exactly what I need it to do, and it doesn't try to force me to sign up for some streaming service I don't want.