Here’s a blog that might answer some questions, and it’s written by a American white guy who’s trying to figure out how race issues and racism are still going down here in the US (and in some other countries with majority populations of people with European ancestry).
I can only talk about my experience. Some people prefer black, some African-American.
I am of recent multiple ancestries, but raised to consider myself African-American. I was taught that by using “African-American” we could know we came from somewhere, just like every person who says s/he’s Irish. Or Polish. Or some other place anywhere else in the world. When I say I’m (also) of Irish, Scots or Italian ancestry, I still get the hairy eyeball from many different people of all races. So for me,“African-American” means that I am not merely descended of people who were enslaved, that the history of my African ancestors didn’t start in 1619 from folks who were magically on a boat at Jamestown Harbor. Until DNA testing is more affordable, most people of African ancestry in the US don’t know what country they come from, or what people. I’ll bet most white Americans know where their ancestors come from!
I have a UK friend born in Nigeria. She knows she’s Yoruban. There’s a form of comfort in that, knowing where she belongs. The racial climate in the US doesn’t allow the descendants of Africans who have been here for 450 years to feel like they truly belong. Most white Americans, if they want, can find out their ancestors’ country’s traditions. We’ve had to recreate a culture almost from scratch.
Consider that before saying something like, “Why don’t people just say they’re ‘American’ and be done with it?” When we’re all considered American, when the image of an “American” around the world isn’t a corn-fed blond kid from the Midwest, when people stop asking each other, “What are you? No, really, what are you?” then maybe we can let that go. In the meantime, we’ve got a lot of questions to ask ourselves and a lot of internal searching as a nation to do about race and class and why they are correlated.