But you're assuming that all Ethiopian immigrants are in some way Black albeit a different Black from African-American blackness. Some Ethiopians may be of European ancestry (i.e. White). "Ethiopian" is not a marker of ethnicity per se any more than "American" is.

As you say, it's complex. Why do we refer to Guatemalans as Latin (o/a/x) or Hispanic when their ethnicity may be something like Nahuatl (which is a general language family) rather than Euro-Spanish? "Indigenous" as an alternative is itself simplistic, a lazy person's catch-all, as though all indigenous peoples are homogeneous, and as if there are no combinations / mixtures.

There is an advantage to the general use of simple categories like "White" and "Black"--it makes discourse easier and helps focus the discussion on what's essential. When the need arises to make a linguistic / ethnographic distinction, then we can do so at that point.