Let’s bring in an academic to this discussion.
Someone already linked the AP guidelines, but I’ll quote an actual professor with a background in this kind of stuff.
Here’s quote from an article written by John McWhorter, a prominent Black conservative who happens to be a professor of English and linguistics at Stanford the subject[1]:
“But what about the black business districts that thrived across the country after slavery was abolished? What about Frederick Douglass, Ida B. Wells, W.E.B. Du Bois, Gwendolyn Brooks, Richard Wright and Thurgood Marshall, none born in Africa and all deeply American people? And while we're on Marshall, what about the civil rights revolution, a moral awakening that we gave to ourselves and the nation.”
“My roots trace back to working-class Black people - Americans, not foreigners - and I'm proud of it. I am John Hamilton McWhorter the Fifth. Four men with my name and appearance, doing their best in a segregated America, came before me. They and their dearest are the heritage that I can feel in my heart, and they knew the sidewalks of Philadelphia and Atlanta, not Sierra Leone.”
“So, we will have a name for ourselves - and it should be Black. "Colored" and "Negro" had their good points but carry a whiff of Plessy vs. Ferguson and Bull Connor about them, so we will let them lie. "Black" isn't perfect, but no term is.”
Are you better qualified to say whether Black should or shouldn’t be capitalized than a Black English and linguistics professor at Stanford? Is your take more academic than his? And if so on what basis? Because it doesn’t seem to be based context or history or what Black people call or have called themselves.
My claim and one his claims is simple: there is a culturally distinct group within America that is called African-American and Black and that the B should be capitalized. Whether The better is Black or African-American is up for debate but only within the African-American community. It’s our right to determine what the proper term is. In the meantime, the consensus is that you should capitalize the B in Black when referring to black Americans who descended from black slaves in America.
[1] https://www.manhattan-institute.org/html/why-im-black-not-af...