Luck in the sense that Katt Williams started to fall off with his bullshyt off stage, Chapelle was in hiding and there weren't any other prominent black comedians doing it big around that time? Yeah, he got in at a good time so the luck coupled with hard work did wonders for him. I think his subject matter which doesn't lean too heavily on the White Vs Black tropes also helped him be universally liked across the board; something a black comic rarely gets outside of the old legends of Pryor, Mooney, Murphy and Cosby. As funny as Eddie Griffin, Chris Rock and Paul Money are, there are LOADS of white folk who don't fukk with getting shytted on so their temples are built largely on their killer wit, story telling art and just naturally stupid nature that's supported by a predominantly black fan base, and that will only get you so far in terms of staying hot in Hollywood.
In regards to your second question, I think he might be but I can't say this confidently since I was never in tune with Jerry Seinfeld during his prime with regards to standup to see if he had THAT big an impact back then. That's what you're asking, right? Because I'm sure it's obvious as fukk that Kevin Hart ain't touching Jerry Seinfeld's starpower if you throw the show Seinfeld in the mix, that's a definitive given. So if you were to separate Seinfeld from his show and base both comedians on their standup shyt, then Kevin should be the clear winner since Jerry Seinfeld grinded out as a mildly funny comic BEFORE the show, working small clubs and had novelty success as a stand up during it and AFTER the enormous fame of Seinfeld. People still weren't fukking with him on Kevin's level in terms of going to see him on stage despite becoming a household name and with the success of Seinfeld, he never really needed to do Standup outside of amusing himself since he was focused on the show and made massive bank off of it.
It's even harder for me now to look up how popular Seinfeld's standup shyt is during and after the show because he's so synonymous with the show that the two are practically merged. As a stan of the show Seinfeld, let me be the first to tell you that a VERY large part of that show's success rests on the talented writing staff they had along with the formidable cast of actors he had to work with. They even acknowledge it within the show when Tv Jerry creates his own show and it flops 'cause no one really found his writing that funny.
Jerry Seinfeld is one lucky motherfukker, but god bless him and Long Ball Larry for creating one of the most memorable shows of all time.
I'll let Kevin Hart cook.