Barely charted? The charts were full of rock bands and songs, you're talking about the late 50s and early 60s.
You're listing singers, I'm talking about bands that wrote music. Real music.
You do realize that a lot of the singers I listed not only play instruments, but also wrote and still write music? Mariah Carey (although I didn't list her) has the most number 1 songs by any artist, all wrote by her. She's second overall to The Beatles. A lot of bands...actually all bands (other than The Beatles) can't even begin to claim that. You talking real music? Dude "real music" is nothing short of an opinion.
I saw somebody on here say that rap wasn't real music. Says who? It's an opinion. And Lady Gaga not only writes her own music, not only has written for other artists, not only plays instruments, but she actually also studied at the NYU Tisch School of The Arts before leaving to focus on her career.
Sia is another person who writes music not only for herself but for others too. But music talent isn't just writing music, its overall performing. When it comes to just overall singing talent and musicianship, I regard Whitney Houston as the greatest to ever step to a mic. I still study Whitney's singing. Her vibrato, phrasing, sustaining of notes, etc...amazing. But that's my opinion. You may disagree and that's ok.
"Real music" and "real artists" is subjective. IMO the artists that I listed above are real singers and musicians