Was I arrested for racism, or because I'm not normal?

It sounds like you were a victim of racial profiling. A young man just cruising a neighborhood where people don't know him, can be considered a suspicious character by those who are from that neighborhood. It is not illegal to walk the streets at night, but next time, you might want to stay where people are familiar with you. Was the neighborhood you were in predominantly white by chance? That could be a factor. I'm just taking a wild guess here. And you did deserve an apology. The cops didn't need to man-handle you like that and if you were so inclined, you could make a formal complaint accusing them of police brutality and racial profiling, but you might want to get some legal support from some kind of agency who can better advise you on that. An agency that advocates for people in your position.