That’s the thing though - individuals learn to accept individuals as who they are. JKR establishes that there is systemic oppression in the wizarding world (house elf slavery is the big one, but it’s very explicit in the text that there are issues with goblins, centaurs and other magical races) - but does nothing to show that the systems have resolved/improved by the end of the series. Individuals learn lessons, but the system is inflexible.

The way that oppression is solved in the books is always through individual action. Even when the wizarding government is implementing policies harmful to muggle-norms/magical races, it’s portrayed as a bad person being bad because they are bad. Draco/Umbridge/Voldemort are individuals that we identify with the oppression itself, so the problem of dealing with wizard racism becomes the much simpler problem of dealing with The Bad Wizards.