What’s interesting is that differences can be mentioned for other physical factors except the brain.
To some extent, you are right. But remember what happened some years back to the sports-handicapping genius in Los Vegas, when he commented on the genetic origins of racial athletic prowess.
The compulsion to believe that everyone is either interchangeable, or potentially equal has a number of roots; but it is of no value to anyone but demagogues & scoundrels. It is also totally absurd. (See Footnote On Absurd Egalitarian Compulsion.)
The breakdown in the Black family structure is a contributor to failure. But so is the compulsive refusal to recognize that there is a vast difference among types of Mankind, in the prevalence of various aptitudes. Again, the denial of reality, helps no one but demagogues & scoundrels.