In my opinion, the only way that we've seemed to make progress here, is when good people, who have power and education, do things. You are talking about the bad people with power and education. Now, if Jesus was a good person, and arguably he did some things that might generally be considered good, I suppose, then I don't see how it is useful to us that he merely left.
We need good people, with power and education, to stick around and help out. And some do, you can find them in history books, inventing things, saying good things. Making a mark that propels the human race forward. Doing things that make life better. Now to me, Jesus is controversial in that regard. He has some good sayings that seem useful, but beyond that, I don't know.
He didn't stick around and invent physics for us, or invent the internet, or planes etc. If he did, we would have 2000 years of experience with those things by now, and they would be better. He cured lepers, but did not show us medicine to use after he died. He let rome have lead piping, which caused who knows what, in terms of biological damage. He didn't say much about how to stop war, etc.
But he has a few good sayings that I remember, that seem to be true. I generally think the 'matthew principle' seems powerful and true, but I think that it also might be a curse? I guess that's sort of the main one, but there a couple others down in my mind somewhere, that I usually remember