No, it cannot be used as a noun to refer to people.
What IS a black? Answer this question and I will concede the point.
I think color descriptors are dumb in the first place— I’ve felt this way ever since I was 11 years old and found out people are “different”. I made a poem about it back then, for a writing contest that I won. Firstly, I’m half Asian so the description doesn’t fit in the first place, but I’m not “Black”, I’m brown. But I digress, I’ve accepted the term Black American/person, begrudgingly. I also ask other Black people not to refer to White people as “whites”. Blacks and Whites creates an ‘us vs them’ dichotomy when speaking, denoting otherness, or even worse, opposite-ness.
However, it’s almost always White people that use the term “blacks” and this term (plural, Black) derives from Blackie or Blackies, which is a racist term.