If you were to be totally honest, you'd admit that the "N" word has a much more heinous history than the others you referenced. Italians, hillbillies, Polish and French were not systemically holocausted for 400 years. "Jew" in and of itself isn't slang. But "kike" would be akin to the "N" word. Horrible history associated with it.
Yes, people often have reasons why "it's different" when something happens to them. In reality nobody is trying to make black people slaves and nobody is trying to re-start the holocaust.
In my opinion the best way to avoid racial problems is to get everybody playing by the same rules, which is what the civil rights movement was
supposed to be about.
Everyone needs to grow up, develop some emotional maturity, and stop flipping out over naughty words.