Hmm.... I have a suggestion if you want more variety of music to look through. You could always look through EDM genres (Which I know is a very open response), as a fair few of them tend to not have lyrics, or only a few words. I'd suggest Monster Cat for that, as they have playlists for specific genres you could check out and it'd always let you explore a whole bunch of different artists too! :D
I don't have any specific character song suggestions, but some specific artists you could check out that could maybe have songs you may want to give to characters are TheFatRat, PegoardNerds, Xomu, and Approaching Nirvana.
I hope this may seem helpful ^^;;;