In America, Black has always been defined not only to describe Black Americans but also as an umbrella term for other individuals who are regarded as Black from different regions of the world, such as Africans (Nigerians, Ghanaians, etc), Caribbeans/Jamaicans, and Afro-Hispanics.
Regardless of how you feel about the term and who should only be allowed to be viewed as such, it's already been set in stone for over a hundred years that in America, the category Black isn't limited to US-born Black Americans, although we are often viewed as the de facto face of what the term Black stands for in regards to ethnicity.
By US standards, Kamala is Black, just not in the Black American sense, but she is classified as Black or, if you want to say, mixed, but still in all Black DNA dominates. This isn't debatable.