The others beside Belle are black-haired, and it's not considered as brunette. The only brunette princesses are Belle and Rapunzel (after her hair was cutting)

^actually black haired people can be called brunettes too

Yep!

Tiana and Snow White.

My favorite!
I don’t feel like brown-haired and black-haired( they are traditionally associated with and tend to symbolize different things since so I still believe Belle’s coloring makes her outstanding and I don’t even consider Belle’s hair dark) belong to the same group but since we don’t have any other DP with brown hair, I understand why you grouped them.

^Isn’t Tiana’s hair dark brown?

And it’s not like I made this up or just grouped them together just because. I actually did look it up and a couple sites did say that black hair are called brunettes too