Humans are an 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. 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 most technology has seemingly been developed by reverse-engineering human designs.
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.
Presumably 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 seems to have constructed at least one massive space shuttle as evidenced by The Ruins of Ark Polaris, which features large amount of English text, along with the eponymous Polaris in the background.
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.
Some Inklings and Octolings may believe humans were never real, as Marina states "I wish humans were real" in Inkopolis News dialogue about Shellendorf Institute.
This line is likely just a joke, as it is only present in English localizations and references a popular Miiverse post that reads "i wish squids were real".[2]
