Some people have a rather pragmatic view of this. He created a TV dance show, just like dozens of others in the days after American Bandstand. So what?
What's important about Soul Train is something that was completely unheard of at the time. Cornelius didn't just create it. He didn't just produce it. He didn't just host it. He OWNED it. The typical show business success story is one where the person is allowed to succeed by a network or a production company or whatever. Cornelius didn't have any of that. Soul Train was his vision and his property, and no one could tell him what to do with it. That's rare in entertainment nowadays. For that to happen with a black man in the white dominated media was a miracle. Remember, there was no BET. There were no networks looking for the easy demographic draw of black audiences (I'm looking at you, UPN). There was nothing like it on TV, and wouldn't be until decades later in those early years of The Arsenio Hall Show before Hall melted down and blamed his cancellation on blacks not supporting his show. (I don't count Showtime At The Apollo. Much as I enjoyed it, it was buried in post-midnight slots. Not a lot of viewership there.)
The ownership thing is not only key from the standpoint of, "Yeah, Cornelius beat the system!", it's also key from the standpoint of what he could do with the show. While the show was ostensibly black and urban, Cornelius had no problem using the show to affect positive change. He gave the world it's first glimpse of the Rev. Al Sharpton. He did an entire segment talking with James Brown about inner city violence back when NO ONE wanted to even acknowledge it. Cornelius also had no problem letting white acts on the show. Elton John, the Bee Gees, and David Bowie all graced that stage.
Cornelius also had a great sense of humor and lack of ego. Probably my favorite non-Soul Train memory is when he was the co-host of the live election special on It's Garry Shandling's Show, showing understated humor that I never suspected he had and making it seem like he'd been doing that sort of thing forever. I don't know why he ended his life. People have been telling me it was a reaction to the early onset of Alzheimer's. Sad, but also understandable.
Cornelius was a true legend. He soared where others didn't because they were afraid or wanted more fame and money or just didn't know how to do it. Rest well, you've earned it.