Since it is popular to claim that the human race originated in Africa, aren’t we all “African-Americans”?
Methinks terms should not be defined into oblivion/irrelevancy.
Ethnicity really only applies (unless in a medical context for objective reasons) to immigrants or 1st-/2nd-generation descendants thereof. Beyond that, they have/should-have assimilated with domestic culture, and genetics should be little more than coincidence at that point.
Elon having literally been born & raised in Africa, by Nth-generation parents, and is a “naturalized” US citizen, he is unequivocally African-American.