Good point. It is far from clear that passage is speaking about human (physical or mental) equality in context, at least in the sense that a racist might assert some “races” are inferior to others by whatever measures of athleticism and intelligence. It seems to be speaking more about a sort of spiritual equality, in the sense that everyone who has faith will get what was “promised”.
I am wondering now, again, what was really intended to be understood by the statement that everyone was made in the image of God? Obviously it can’t have been meant that we are all absolutely equal in all measures of physical and cognitive performance(the kinds of crap that matters to racists). Innumerable people are just better athletes, better looking, and much more clever than I am. And after all, even superficially we all do look different, we are not identical clones of each other. So something else must have been meant by that statement or it would be directly obviously false. Perhaps this equality was only ever meant in a sort of spiritual sense.
But then the Christian has no basis for referring to these passages as a putative refutation of racist ideologies that derive from beliefs about human physical and cognitive inequality, as they are simply referring to a completely different measure of human value than the one the racist is referring to.