Robert, much of what you write here is incoherent. E.g. the above means what exactly?

Then you ask why do black people from Africa or the Caribbean fare better in the US than those who have been here all along?

Assuming for the moment (though I shouldn't) that you're right about the above, there are a number of reasons. Take, for example, the GI Bill. Signed into law in 1944, it set the stage for one of the most massive transfers of wealth in any nation's history, & created the post-war middle class. But the 1.2 million black veterans (from wwii alone) were largely excluded.

1) Black GIs were more likely to receive less-than honorable discharges.

2) Neighborhoods were they were permitted to buy homes were often redlined & banks refused to lend them mortgages, even with VA co-signing. Out of 67,000 mortgages cosigned by the VA in NYC, only 100 went to black borrowers.

3) Black veterans were insufficiently prepared for college-level work, & encouraged, by the VA, to take vocational training instead. Those that did attend college were often limited to historically black institutions which, at the time at least, were not accredited, & thus not eligible for loans.

4) Black veterans were often denied the unemployment insurance of $20/month if any work at all were available, even if it paid less.

In short, black veterans failed to benefit from the boon their white counterparts experienced, & thus had less wealth to pass on to their baby boomer children & so on.

If you're interested, Ta Nehesi Coates's The Case For Reparations describes even more recent scams & examples of red-lining that didn't afflict black people exclusively, but did impact them disproportionately.

And that is why black people from other parts of the world might do better here, because in part they arrive with more, with an economic heritage less tainted with theft & discrimination.