<< it just encourages us to separate into tribes which can then battle each other. >>
WTF? Talk about reading too much into it. Granted, the question of race or ethnicity has so many facets that we could debate about the particular divisions for years. Fact is, some people are proud of their heritage whether or not they are American (and many people on this board are NOT American -- I can think of half a dozen without even trying).
I have no problem about asserting my ethnicity as Polish. My maternal grandmother was born in Bochnia, Poland; my paternal grandmother's family was from Poznen -- probably some German there; my maternal grandfather's family was likely from eastern Poland -- could be Russian or Ukrainian actually; and I'm not sure about my paternal grandfather's family. It's a link to my past, and I could see the family resemblence in the faces of the Polish people when I visited there in 1993 (Cracow and Warszawa, or Krakow and Warsaw if you want to Anglicize it). We have numerous Polish traditions in my family, and both of my parents spoke some of the language as children.
Everyone in the U.S. is from somewhere. Even the "Native Americans" (a term that I frankly find offensive since I was born here) derive from nomadic Asian tribes though their claim is much earlier. We're all actually eastern Africans if you want to look REALLY far back. It's a harmless question unless you want to make an issue where there is none.
Oh, SHUX? Could you please change that sig? I absolutely despise that "poem". Try something by Keats. 😀