That's absurd.
Redskins is slang and it was meant the same way n1gger is.
Spartan isn't slang. Nor derogatory. Buccaneers and Pirates are outlaws, like Raiders. That's different. Athenians, I don't even know where you pull that from. Celtics isn't derogatory. Mics would be. Demon Deacons, I'll have to check on that one. And I have never heard the term 'jimmy hat' in my entire life. Ever.