iTunes is bloated. If you just want to play some mp3s like you did in the old days, try Tiny Player for Mac.
Download, drag to Applications, and open. (If your Mac doesn’t want to open this “unrecognized” app, open with the right-click menu.)
Tiny Player doesn’t have the many features of iTunes, or even of VLC. It has no equalizer, or cover art, or “related music.” It just plays your music files, in the order you tell it, with or without shuffle and repeat. Good.
Tiny Player also plays FLAC, AAC, AIFF and WAV files. (Playing FLAC requires High Sierra, as I learned after an extremely pretentious attempt to play a vinyl-ripped copy of “Tubular Bells 2003.”) It can save and open m3u playlists.
For more features, like Last.fm integration, folder view, and a media browser, try the classic lightweight Mac music player Cog.