Given that each planet seems to have one species, except that humans live everywhere, I always kind of assumed that the Galactic Empire was one with humans at the core.
The Galactic Empire showing a clear citizenship "caste" favoritism of Citizen/Officer Humans, General Humans, Cloned Humans, Aliens, and then Droids, but also working with all of those at the same time in its military efforts (there are a few aliens in the Empire's military, there are a lot of droids) does seem imperial in the way the article suggests, especially because that core of clear "Citizen/Officer Humans" seems so relatively small versus they armies they command of all the other types.