Remarkable, perhaps? I'd hesitate to use "incredible" because his background privilege and wealth makes it all... well, more credible; and using such an unalloyed, positive word feels wrong given the costs to his relationships and his promotions of far-right groups and conspiracy theories. His path is unique, but it's believable and nuanced.

That's beside the point though, which is that you can't say something being "incredible" is a fact. It's a subjective judgement.

So I should have said “remarkable”?

Sure, I can do that.

No, you're still missing the point. "Remarkable" and "incredible" are not objective ways to describe something.