system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why are so many of the central figures in Galactic history human?
gpt
By simple virtue of the fact that humans are the most numerically superior species in the galaxy. Humans spread all over the galaxy and colonized every world possible. There's simply so many of them that it's difficult to avoid their influence. 

Of course, by the time of the Empire, anti-alien prejudice was in effect and there were deliberate efforts to prevent non-humans from doing anything too important.