There's some conclusions that I disagree with here assuming the same starting facts. Also, I think calling things "racist" or "segregated" usually ends critical thinking because they have the same emotional label as the initial definition (systematic differences in treatment due to skin color) even as the definitions have expanded (systematic differences in outcomes, independent of cause).

Let's presume that intelligence is heritable. Given the difference between humans and other species I do not see how this can be argued.

Let's also presume that intelligence varies between humans. If there is no variation across a population, then it cannot be selected for, unless you argue a stepwise change that's completely uniform, for which I don't see any other evolutionary proxy.

Let's NOT presume that intelligence varies between races.

My question to you is this:

Can the children of a group of humans selected for intelligence (e.g. completed enough education despite a cultural revolution, had enough finances, etc. -- Asians; escaped systematic genocide, etc. -- Jews) be, on average and not uniformly and with lots of overlap, smarter than the children of a group of humans not selected for intelligence (e.g. sold by other Africans into slavery, so presumably disadvantaged in the original African society, lower-educational-barrier illegal immigration as with many Central and South Americans)?

Note for the purposes of this question that reproduction within each group (Asian immigrants : Asian immigrants; Jews : Jews; African-Americans : African-Americans; Hispanics : Hispanics) is much larger than reproduction between groups, preventing admixing over time.