The only group that can claim they've been more oppressed in America than blacks are Native Americans, because they were outright GENOCIDED.
I was watching a very interesting historical vid yesterday about how after slavery ended, black people were routinely arrested on petty charges and then had their labor sold to financial interests in the South. This shit went on until the mid-20th century. And we aren't talking crimes like murder and rape, we are talking crimes like "Riding the Railroad without a ticket."
The problem is, you can't point to any one date and say, "that's the day black people started being treated fairly". Because that date really hasn't happened yet.
Hmmm... Let's look at that.
Here's the thing. Those "other groups" didn't have 250 years of slavery followed by 100 years of Jim Crow. The point is, they were never allowed to assimilate.
I could make the argument that my grandparents, when they immigrated from Germany in the 1920's (When the little town in Germany they lived in was occupied by the French) probably did encounter anti-German prejudice. But at some point, they were considered "White enough" to assimilate. My dad was able to marry a non-German woman. (Something that a black person couldn't do in parts of this country until 1969).
The key thing was immigration was a choice. You move from something bad to a little bit better. Slavery wasn't a choice. You got kidnapped, you were put into something a bit worse. When slavery was ended, it was replaced by something that was in some aspects, worse than slavery. Debt-prisoners were treated MUCH worse than slaves. At least with a slave, you had an obligation to keep him healthy because he was an asset.