I mean, every law will inevitably impact different groups at least a little differently. I'm not a fan of obsessing about race every time a law is written, no.

>What alternative history must one subscribe to in order to believe that ignoring disparate impact won’t end in humans rights abuses?

This seems like sloppy reasoning. If a person's rights are being violated, they ought to be able to make that argument in court without reference to disparate impact.

What we've seen in the US is the 90s "judge people as individuals" paradigm has been replaced by a "racial collectivism" paradigm. In recent years, this new paradigm was initially mainstream on the left, then became mainstream on the right:

https://www.youtube.com/watch?v=Ev373c7wSRg

The "racial collectivism" paradigm is corrosive to individual rights, no matter who wields it. Furthermore, collectivist activity on the part of one ethnic group ends up being countered by collectivist activity on the part of other ethnic groups, in a doom spiral. The result is descent into hateful sectarianism. Scroll through X on any Tuesday to see what I mean.

>nuclear testing and proliferation disproportionately impacted the Navajo nation especially because they had absolutely no recourse against it? Are we just supposed to say “tough luck”? “Might makes right?” “Should’ve gotten a better lawyer?”

Consider a hypothetical where the town near the nuclear test has a population which is a perfect microcosm of the US in terms of race, gender, age, class, etc. No "disparate impact" argument can be possibly made in this hypothetical, since all of the racial "collectives" are equally harmed.

Does this change the fact that the nuclear tests are harming people? Or the best approaches to the problem?

Racial collectivism just isn't a good approach. People are more responsive to the needs of others when they view them as fellow humans or fellow citizens, not representatives of alien collectives.