Unfortunately, the name of their planet of origin (In the Star Wars franchise) has been lost to time. Though it is possible it may be Alderaan or Corellia, as Humans have been natives to those planets for as far back as records show. Humans have leading members of the Galactic scene for a long period also, perhaps simply because of numbers. Humans were among the founding species of the Republic.
During this period, humans gained much power in the fact that the Republic's armires were made up of Clones of a Mandalorian Human, and were therefore, essentially Human.
They have held postions on the Republic's senate up until it's disbansion by the Supreme Chancellor. After the Republic's collapse at the hands of the Supreme Chancellor, Humans continued to hold much power, politically and militarily, but this time, it was near-absolute power because of the Empire's Humanist policies.
The Empire's prejudices is most of the reason the GCW started, as many species could no longer take the Empire putting them down, purely for Speciest (similar to Racist, but on a grander scale) reasons. Many humans also rebelled, as they either could not take the Empire treating other species as terribly as it was.
Example = Han Solo