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.
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.