Your argument suffers from what I call the “starting line” problem. Yes, in a perfect world, there is no difference but because we manufacture difference, we are not all equal.

Slavery, Jim Crow, Legal Discrimination, White Flight, Employment Discrimination, Housing Discrimination and a million other things ensure that we don’t all begin the race from the same “starting line.”

There is good reason that MLK’s “content of our character” line comes AFTER a bunch of arguments about existing and real inequality. It was his DREAM that eventually equality of situation would become real for people of color.

Maybe check out the Space Traders by Derrick Bell (could suggest a ton of books you might or might not have read as well).

I could do a song and dance about Gender too, if you want?