Humans are a presumably extinct species that once populated the world 12,000 years ago, before the start of the Mollusc Era. It is stated that the rising sea levels caused the extinction caused by a massive apocalyptic war. This cataclysm killed most of the population and the rest attempted escape underground or into space. While none are known to have survived to the present day, many remaining artifacts from the humans are still present and discovered by the current inhabitants, such as Inklings. Human fossils and bones have been found and are exhibited in museums, and reverse-engineering human designs has seemingly developed most technology.
Currently, the only specific human being that is known is "the Professor", who created the Telephone, an AI designed to pass down humanity's knowledge to the next intelligent life, but which reprogrammed itself to recreate life to its specifications after deeming Inkling and Octarian society unworthy of its knowledge. The professor was also Judd's original owner,[1] and cryogenically sealed Judd in a machine to preserve him for the future. The machine is also capable of creating a clone of Judd when reactivated, as the human feared that the cat would be lonely.
Prior to their extinction, Humans built large networks of underground dome cities to escape the rising sea levels. These domes were seemingly abandoned by the time following The Great Turf War. Humanity also attempted to fly to space in hopes of finding another habitable planet, as evident of the Ruins of Ark Polaris. Many species of Earth were taken on board the vessel too, and were presumably tested on. This plan failed however, as the Ark Polaris was hit by debris at the edge of the Solar System, and was left to float aimlessly in space for ten thousand years, before inevitably crashing into Earth. The only known surviver of the crash was Bear #3.
Return of the Mammalians reveals that humans were indirectly responsible for the genesis of the sentient life that exists in the Mollusc Era, as the humans of Alterna had developed a form of liquid crystal based on squid bodily fluids that reacted to thoughts and emotions; following the destruction of Alterna in a failed attempt to recolonize the Earth the crystals entered the underground seas, infusing the marine life with humanity's lingering emotions and drastically accelerating their evolution.
The Art of Splatoon expands on Splatoon's background story, revealing that the extinction of humans was caused by a nuclear missile detonating on Antarctica during one of a series of wars, which melted its ice cap and worsened the already rising sea levels.
In the same art book, it is also implied that humans created the Octarian domes found in Octo Valley as an unsuccessful shelter during the flooding.
The NILS Statue resembles a giant human being, more specifically the mythological Greek god Hermes.
English (both American and European) and Mexican Spanish localizations of the Inkopolis News dialogue of Shellendorf Institute reference humans, with the English localizations in particular also referencing a popular real-life Miiverse post that reads "i wish squids were real".[2]
