I was just thinking about this these past days, as I'm thinking a lot about differences in the diasporas. Like someone already said, Black Americans have been in America for centuries and built the country, so it's theirs in that sense. I never thought about it but Africans were deported there not so long after Euros invaded. So they can claim it at least as much as White Americans, knowing that neither group is native.
A big difference with the diaspora in Europe is that we (for the vast majority) know precisely which country we originally come from...and usually still have some link (music, culture, language, family...) with it. That's why Africans in Europe might more claim their country of origin, because they can. Black Americans can't really do that, not by their own fault of course but it is what it is, can't rewrite history. And finding out with those genetic tests doesn't really help, unless you follow that with thorough research, and even then it will still feel "foreign" to a degree. In general diasporas have a strong link to wherever they originally come from, regardless of how long they left, thanks to language and culture (Jews, Armenians, Palestinians, Kurds, etc...). In that sense Blacks in the Americas are kind of an exception, and I don't even think most would consider themselves part of a "diaspora", since that would imply a strong connection to a "motherland" they really don't know much about.
What I don't understand is why Black Americans claim America but call "c00ns" Black Europeans claiming whatever Euro country they claim as if Europe wasn't built on the back of African ressources too, including African workforce (we all know about Leopold II). It's the same uber-capitalist western imperialism that built Europe and the US, only difference being that Black bodies were exploited far away in Europe's case.