Racism is incorrect. It's simply false. Average differences between races are dwarfed by individual differences between humans. This is not an assumption that the past is morally inferior. It is a simple observation that when you eliminate confounding variables, racial differences simply don't account for differences in group behavior and outcomes.

You'd have better luck grouping humans by height, saying that we all know that a society full of people taller than 6' simply cannot govern themselves. We could group humans by whether they're left-handed or right-handed, whether they like cilantro or think it tastes like soap, whether they can smell asparagus in their urine, whether they have that widow's peak thing in their hairline or not, the shape of their ear, or the color of their skin. There is no evidence that skin color is more meaningful than any of those other groupings: it's simply more obvious and carries enormous historical weight.

You're wrong that the question can't be asked: it can. I've seen it discussed in the context of professional sports, where it may play an actual part -- nobody was banned for that. As far as societies effectively governing themselves, the question has been asked, again, and again, and again, and again. The answer is always the same: race isn't what matters. And every time someone decides we need to figure this out again, millions have to suffer and die. If you have new evidence, present it.

> a question leading to a racist conclusion disallows the questions entirely

This is called "proof by contradiction". Any answer to a question that leads to a known-false conclusion is therefore not the right answer to that question.

>Progressive ideology fundamentally assumes that the past is morally inferior and thus it is unthinkable to question if things were better in previous times

What are you talking about? The progressive left frequently talks about the past be being better when it comes to the worlds increasing wealth inequality and how wages stagnated.

Can you stop speaking in strawmen and make an actual point? Are you dancing around an assertion that apartheid was better for South Africa?