Rather than focus on the race issue, I'd like to say that Manning was a genuinely funny comedian, in my opinion, even if his material did appear outdated later on in his career. He was unfortunate in some ways to be singled out by the media when there were and are many other comics from his era who tell exactly the same type of jokes.
I hope that the tributes that will follow his death will not just focus on one aspect of his work but will instead try to look at what saw him establish such a long and successful career.