I thought your claim was that the harms to black families aren't just the sum of the different averages of their economic environments. That second paragraph was saying that the two are correlated. Am I misunderstanding?
The claim that racial differences are incidentally correlated (whether true coincidence or particulars of history) with economic environments is not a good argument that we should tackle inequalities in those issues at the racial level. Surely the latter only holds if you can point to causal effects.