It is true that all of world history is data, but it is not necessarily data that can answer any particular question. The problem is the age-old nature versus nurture debate. Both genetics and environment are important to IQ. Both generally affect IQ through long, convoluted, and poorly understood reasons of cause and effect. Therefore we can establish evidence of differences, but can't necessarily distinguish between theories about the causes of those differences.
What would make a difference is a theory of mechanism. For example it is uncontroversial that people with ancestry from Nigeria are better at sprinting, and people with ancestry from Kenya are better at long distance running. For this we can identify specific facts about body type that help with sprinting versus long distance running, and we can identify strong evidence that these body type differences are due to genetics.
But we have no such theory of mechanism that can be applied to IQ. And therefore the mass of data we have about the existence of differences does not distinguish between potential causes of said differences.
We can also verify that differences in thinking speed between individuals has a large component due to genetics, and also another large component due to environment. Everything from diet to the quality of parental interactions in early childhood.
What we can't determine is to whether genetics contributes to the differences in thinking speed between groups of people. We can identify important environmental factors like culture and racism. We can show that environmental facts matter. For example children of mixed race couples have a higher average IQ if they have white mothers. But nobody has found a way to measure what difference genetics might or might not make.
World class sprinters have an over-representation of individuals descended from a specific region of Nigeria - you can't generalize that to "Nigerians sprint faster than Europeans",or "Black people sprint faster than white people" the way people do with IQ. It is also prudent to note that Kenya has a whole ecosystem nurturing long distance runners; with a wealth of academies, trainers available to the young who show some talent, so ascribing Kenyan's prowess to nature alone is incorrect.
Nutrition and IQ are correlated independent of race; especially early-childhood nutrition. Standardized testing is further compounded by test prep and tutors (proxy for wealth). Wealth in a family correlates to parents' education level. The lack of education in older African Americans has an obvious historical explanation. Most black Americans are descended from slaves from West Africa, but don't do as well as recent West African immigrants - 29% of Nigerian-Americans have advanced degrees; more than any other immigrant group. "Nature" doesn't explain the stark disparity of academic outcomes between two groups that are both of west African descent.
Does all of world history count as data? What should we go by? Propose a test.