Hehe, it's funny, I wasn't sure what position you were taking exactly. But when you said that trying to change the world was folly, I thought you were arguing against the main premise of my argument. I think I understand you better now.

that we--all of us--need to be better people in order for larger, systemic changes to succeed

In order for us to be able to make the changes, yes, definitely.

What have the accomplishments of Elon Musk, and Facebook, and Google done to make the world a freer place?

That's an interesting question but I mentioned them only to rebut your claim that "the only power any of us really has is decidedly local." If those individuals, and others, can have a global impact, so can we.

but the only acts on Earth He performed involved the people in his immediate proximity

But those acts reshaped the Roman Empire and indeed the world after his death. That's his influence, no matter when it happened.

We live in a very different world now, thanks to technology. We can change the world very quickly now and with less work than before.