Human High Culture, also called High Human Culture and High Imperial Culture or Human Supremacy, was the Galactic Empire's codified policy of Humanocentric speciesism. It centered around the belief (long, if privately, held by a minority of Humans in the Human-dominated Core) that Mankind was inherently superior to other species.
There were several undertones that carried over into anti-droid sentiment and anti-female chauvinism, which also manifested against Human females, who were almost universally barred from the higher echelons of power in the Empire's military and government. Exceptions included Admiral Daala of the Imperial Navy (promoted in secret by Grand Moff Tarkin), Admiral Betl Oxtroe, Intelligence Director Ysanne Isard, Captain Uwlla Iillor of the Black Asp, and the highly decorated Pilot Juno Eclipse.
Those not meeting the standards of Human High Culture were marked as being Non-huMan.
At the time of the foundation of the Galactic Empire, there were several active, minority populist groups on Coruscant that advocated concepts of Human supremacy. These were quickly assimilated into the nascent COMPNOR. Their views were then coalesced into a coherent vision primarily by Crueya Vandron, Ishin-Il-Raz, and Sate Pestage.
Non-Humans were treated as second-class citizens by the Empire
The chief tenet of Human High Culture was that Humans were the only truly intelligent and productive members of any society. They cited that it was almost exclusively Humans who had formed and led the Old Republic and the Human worlds of the Core were some of the oldest, richest, and most advanced in the galaxy.
As such, through the repealing of such laws as the Rights of Sentience and the creation of new acts, all nonhumans were made second-class citizens (if citizens at all). Non-Human slavery was re-legalized. Only 'pure' (i.e., those made exclusively by Humans and with no help from nonhumans) works of art (such as operas, holovids, or books) were allowed to be produced, viewed, and spread, since only Human culture was worthy enough to be allowed to prosper in the New Order. Non-Humans were 'actively discouraged' to participate in government or join the Imperial military, and Human governors and moffs were placed in command of nonhuman worlds and sectors. There were loopholes, however: if non-Humans and Near-humans were devoted enough to Emperor Palpatine, and focused solely upon serving his Empire, then they would be left unmolested. Examples of such tolerance were Grand Admiral Thrawn, Grand Moff Bertroff Hissa, and General Bentilais san Sk'ar.
It could be argued that any roots for Palpatine's bigotry could be traced to the traditional animosity that dominated relations between the Humans of Naboo (Palpatine's home planet) and the Gungans who cohabited that world. However, It is debatable to what degree, if any, Palpatine was a speciesist. Palpatine freely consorted with nonhumans such as Mas Amedda and Sly Moore, as well as being an apprentice to Darth Plagueis (a Muun) and taking Darth Maul (a Dathomirian Zabrak) as an apprentice, all of whom were Humanoid. Therefore, it might be suggested that as a Sith, Palpatine's Humanocentrism was more liberal than that of the standard Imperial view, possibly due to the fact that Sith throughout history were predominantly either Human or Humanoid. Palpatine, or rather Darth Sidious, indicated in the Book of Sith that he did not personally adhere to Humanocentrism himself, but nonetheless viewed it as useful for ensuring a tighter grip on the Empire. From this viewpoint, it is conceivable that Palpatine's speciesism was broadened to include certain Humanoid species and that he used anti-alien sentiments as a way to divide the beings of the galaxy and help consolidate his rule. In fact, among the atrocities Palpatine committed was the destruction of the Human-dominated world of Alderaan and the creation of a pathogen that targeted Humans exclusively.
Even so, Wilhuff Tarkin, lieutenant governor of Eriadu who commanded the Republic Outland Regions Security Force, but also a covert servant to Sith Lords Plagueis and Sidious, clearly enunciated a Humanocentric view that on first blush would appear to reflect the genuine galaxy-view of his dark side superiors. To Raith Sienar, in 29 BBY, Tarkin announced that he performed "favors for certain people" for whom "balance is no longer necessary." These powerful, highly placed individuals held a preference or "appreciation for fingers—not tentacles ... not palps, but human fingers—reaching into a great many stellar soup bowls, testing the temperature to see if they are ready for the eating ... Mark my words, Raith. Humans are the future"; to which Sienar, himself a Human and a future servant of the Galactic Empire (designer of the Imperial TIE Fighter and the originator of the Death Star concept), noting the tension in Tarkin's voice, responded, "So marked." Indeed, Sienar had sensed, as Tarkin now affirmed, that a shift in the "political psychology" of the galaxy was underway, that those beings who would soon "replace" the Republic's "effete elites" (beings who were rigid, inflexible, outdated) would "rule by brutality"; it was, in fact, "a law in the history of the galaxy. A kind of political balance, frightening but true." It was to this imminent perceived shift towards brutality in political rule that Sienar, only months before, had turned his "craft" of weapons and ship design (pursuing just such an angle of brutal, "centralized strength," though now he understood it was to take Human form) when he began work on his Expeditionary Battle Planetoid, whose design presentation had left Tarkin "entranced." The Eriadu commander was quick to admit, however, that due to "the tolerance and weakness of our predecessors ... it could take decades to make humans the supreme race in this galaxy," requiring of them a magnanimity towards lesser races "for the time being."
Darth Sidious' apprentice, Count Dooku (Darth Tyranus), was apparently also a Human supremacist who desired to see the Republic transformed into an Empire of Man, with the Sith as its army. However, it is possible he developed Humanocentric opinions late in life from his association with Sidious, as in his youth he had alien friends and it is difficult to believe that any anti-alien sentiment on his part could have been hidden from the Jedi for seventy years. Many of his hand-picked Dark Acolytes were nonhuman, and he also seemed to personally respect Geonosian Archduke Poggle the Lesser.
Human High Culture was enforced and imprinted upon the Empire's citizenry by the Coalition for Progress, Imperial Board of Culture, and the Sub-Adult Groups.
The views of Human High Culture would be kept alive in the New Republic for years after the Empire's defeat by fringe groups such as the Human League. At the same time, Admiral Daala strongly weakened this concept within the Imperial Remnant by allowing aliens of all kinds to join the Imperial military. By the time of the Fel and Sith Empire, several aliens served within the Imperial military as stormtroopers, officers and even Admirals. However, by 137 ABY, individuals such as Admiral Dru Valan still believed in the innate superiority of Humans and resented serving under non-Human officers.