I'm going to agree with you... But with some big caveats.
First on a personal level it's always the screw ups fault, but on a societal level there can be reason why certain races/classes/genders/whatever produce more screwups.
But your absolutely right, Africans are wildly more successful here than 'African'-Americans. This helps demonstrate that racism isn't the entire problem. That doesn't mean racism doesn't exist, or doesn't hurt, because it does. But ending racism wouldn't be enough to fix things for black Americans at this point. A huge part of the problem is classiscm, and an even bigger part is that racism and classiscm stack really badly.
To make up numbers say racism makes life 5% harder and classiscm makes life 10% harder, instead of both combining to make life 15% harder its more like they multiply and life gets 50% harder. Obviously I invented the numbers, but does the general concept make sense? This is something I've only started to fully understand recently and that I think many people miss.
In America African immigrants tend to arrive with an upper-middle class value system, much like stereotypical Asian immigrants do. It serves them very well, but it isn't shared by poor inner city blacks born in America. There problems are very deep and I don't really know the solution, but yelling about boot straps won't do it. Even ending racism won't do it, though it would help.
The fact is past racism put them where they are and just taking away the racism hasn't/won't fix the communities. When an individual has a chance and blows it, well screw them you shouldn't blow your chances. But we can't extrapolate that to an entire community.