Honestly... it's complicated. As I understand it, African-American is one of the more recent ways of saying (with the intent of being polite) that someone is a black skinned and ethnically African and is American.

The term was not meant to extend to corner cases like mine - I'm white, but one of my ancestors grew up on the African continent in an island in the Atlantic and spoke Portuguese.

I suspect that this term will fall out of favor soon and be replaced by another.

Americans of European descent tend to refer to themselves by nation of immigrant origin (eg: Italian American, Irish American, etc.)

However, because African slaves brought to the New World were denied the ability to culturally identify with, or even know (after generations) which African nation or tribe they descended from, the only common cultural identity they could form, apart from that which slavery had forced upon them, was as a diaspora from "Africa" as a whole.

"African American" is a term with a specific cultural and historical context behind it linked to the identity of the descendants of slaves and to black immigrants from Africa, and there is controversy about its use even within the black community, but it isn't going to correctly refer to the descendant of white Dutch colonizers in South Africa even if it does technically fit. Or at least not without coming across as racist itself.

Consider that racist if you like, but race and culture are messy and complicated everywhere, not just in the US.

"Colorblind" often means pretending racism no longer exists and ignoring it, or worse, considering it racist to do otherwise.

While it might be nice to live in a "post-racial" world, it should be obvious that we don't, yet.

African American != South African immigrant.

What if the South African immigrant was black and had lived in the US for 40 years?