Sorry for the hiatus in discussion; I have broken two fingers. I don't think I have the typing stamina to get to all of that, but to react to your last question: when a social arrangement has racist effects, that social arrangement is racist, and will improve by becoming less so. Although you haven't really defined "class" here, one couldn't make the same statement about any sense of "class" without some caveats.

Your example seems to be a largely static one, which is neither realistic nor particularly illuminating. Policing like any "modern" phenomenon is relatively recent, so we should examine the entire narrative of effects rather than taking a snapshot and presuming it to encompass the whole range of possible experience.

Race admits to much less mobility than most other pretexts for oppression. That is bad because it makes society less agile, and because it kills hope and confidence. Both of those emotions are entirely beneficial, so their loss in any subgroup is harmful.