What happened to the one drop rule?
That is an interesting discussion. While racist whites invented it for their purposes, it was also useful for black people to unify across tonal values because of it.
Prior to the 70s, virtually all "light-skinned" black people were the result of, well, "selective breeding" within the black community itself. Interracial marriages were, as you know, illegal in 16 states and strongly discouraged by Draconian social measures nearly everywhere else. And while light-skinned blacks got a small amount of "privilege" in some areas, being light-skinned never got anyone past a door marked "white," which meant "none of us is free until all of us are free" had a meaning. Even Lena Horne was forced to pee in a Dixie cup when entertaining in white venues, because she wasn't allowed to use the white-only restrooms.
Things changed after Loving v Virginia, in which a white man took the state to court for the right to marry anyone he wanted (being white and male didn't yet afford all the privilege he craved). The result was a boom of interracial marriages and biracial children in the 70s and 80s.
And then, suddenly "biracial" became a thing in the 90s. Prior to the 90s, it was not a thing of any social recognition. It was white mothers who created a new social group to separate their children from being considered "black." Interestingly, biracial children tend to "identify" according to the race of their mothers, with the biracial children of black mothers more often identifying as black while the biracial children of white mothers tend to identify as...not-black.
So, the US (specifically, white women) has now created a whole new racial category it had not had before, "biracial." This has had negative implications for "unambiguously black" people, particularly unambiguously black women, who see themselves being erased from media. I'd mention again that white women do most of that media casting, which is something unambiguously black women will also mention.
My daughter happens to be light-skinned in the "old fashioned" way--her mother and I have some Caucasian genes like most of us, and she got one of those random combinations that brought her out lighter skinned than either of us, although her features are typically full and her hair is typically curly. She has never considered herself anything other than ADOS, although she's had the lower-middle class upbringing typical of a military brat, raised in the ultimate of gated communities: Military bases.
She was ostracised in public schools in the 90s, however, by unambiguously black girls who presumed she was biracial. And she has been surprised in recent years to find that she has been the unknowing recipient of "biracial privilege" with the white CEO of her current company. She realized it when she was in meetings with him and he kept mentioning his biracial grandchildren to her: "...you know, my grandchildren are biracial, too...."
Black activists are on one hand denouncing the "one drop rule" because they want to clearly separate biracial people from the unambiguously black, and at the same time they're developing further distinctions such as "multi-generational biracial" for people who are lighter-skinned but have traditionally black-identified parents...such as my daughter. "Multi-generational biracial?" It seems to me that category would include pretty much all of us ADOS blacks, if DNA tests be told...but, oh, well.
This is a whole new social change, and we don't know where it's going to go.