CHARACTERS
Following humanity's extinction, Splatoon's world is populated by a mix of various anthropomorphic —mostly sea-based— creatures
species
The two predominant species that now inhabit this Earth are INKLINGS -descended from squids- and OCTARIANS -descended from octopuses-. Let's just say they don't have the best diplomatic relations, and it's the inkling that have come out on top.
Other species rendered humanoid are: jellyfishes, sea urchins, anemones, salmons, crabs... and many more aquatic friends!
There aren't many characters by way of humans...that is to say there are none. There aren't many mammals either, except of course for our Turf War referees Judd and L'il Judd...and maybe a cerain grizzly.
There are also some non living characters: friendly neighbourhood A.Is like Commander Tartar or O.R.C.A.