Manabi

And on the extreme end of that was the Duras family being more like the stereotypical Romulan (and even allying with them against their own people) than a Real Klingon™. It was disgusting how they managed to keep their house throughout the series, even though they were everything a Klingon wasn't supposed to be.

I think it was less humanity's greatness that allowed them to reach the stars in the alternate timeline and more of having no choice but to do so. Earth was a wasteland and they needed more resources beyond what was available in the rest of our solar system. La'an told Kirk at one point that he could be an explorer in her timeline, heavily implying humanity doesn't do that in his.