As for the question about American blacks vs. black foreigners or recent black immigrants to the U.S. Here's a key distinction: the descendants of American slaves relatively often -- and understandably -- have a pathological culture. By contrast, black people who immigrate freely to the U.S. from the West Indies, for example, are a very successful group economically -- according to some research they are more successful than the average white family. They get educated, become professionals, and are prosperous. They generally have a reasonable modicum of respect for duly constituted authorities.
The implication is that the pathological culture of many native Americans blacks is the result of the brutality of slavery. What the poster apparently doesn't realize is that West Indies slavery was - much - more brutal than American slavery. To the point that they could not maintain their population and had to constantly import replacements, with 95% of black slaves going to the Caribbean and S. America, only 5% to N. America, where slaves thrived and multiplied, almost uniquely in world history.
Slavery in the Caribbean lasted almost as long, with emancipation in different areas coming from 30 years before ours to over 20 years later. There are good questions to be asked about why the long-term effects of slavery were so different in different parts of the world. Or if a history of slavery really has much to do with it.
Recently worked a project in Grenada, 95%+ black. Several different Grenadians commented on how perception of West Indies blacks in America is driven by Jamaican gangs and thugs. At least according to them, this is a result of widespread adoption of Cuban marxist ideology of hate rich people and whitey in Jamaica. To the point where even native Jamaicans who became rich (by local standards) in USA or Britain can't return to Jamaica without being targeted.
IOW, the West Indies is a big place, with some pretty diverse populations.
And dramatically different social successes even on the same island: Compare North and South Korea (er, Haiti and Dominican Republic) lifestyles and health and economies and ecologies.