Yes, it tells me that there's massive socio-economic, financial and educational opportunity inequality in the United States, which acts as an underpinning reasons why there's massive disparity in crime statistics as a result.
You know, rather than what I have to assume is your assertion that blacks are
genetically more predisposed to murder and violent crime? Because I quite literally cannot see any other way out of your assertion here whatsoever...
As for the rest of this rambling post... they aren't unique in having the suffix -American as a group - Asian-American, Oceanic-American and Latino-American are also used. And it has absolutely nothing to do with anything whatsoever.
Oh, and also, just for fun:
https://en.wikipedia.org/wiki/List_of_ethnic_groups_in_Nigeria
Or, to summarise, what the hell are you talking about lad?