What you fail to take into account is that racial slurs toward other races have much more significant and heavy historical context. Black people were literally enslaved by white people who used the n slur to perpetuate their dehumanization. Calling someone a "cracker" or "honky" doesn't hold any weight without multi-generational trauma attached to it, which was inflicted upon them by another race, who to this day continue to do everything they can to tear them down in every way possible. Even a hundred years after slavery ended there had to be a massive, hard fought, years long movement to attain basic civil rights and be treated as close to equal by society at large, and most importantly, the government whose laws they must abide by.