Human Language is a language spoken by humans, although some animals speak it as well, notably Parrot King, Commander ApeTrully, Jumpy Ghostface, Golden Eye Husky and the Zebra Brothers. It is rendered as real-world English most of the time.
Sometime prior to HighRoller's war, Parrot King used to teach human language to animals, but his lessons stopped once he was convinced what HighRoller told him was true, about humans being evil liars. However, Commander ApeTrully told him HighRoller was the liar, and this was confirmed using Parrot King's snail. Parrot King then decided to teach the animals of Big Green to speak human language, and Jumpy Ghostface eagerly joined his class.
- Human Language is usually rendered as real-world English, however has been rendered in Chinese at times, as seen in "Parrot Castle", when Commander ApeTrully said "Laoshi Hao" to Parrot King, meaning "Hello Teacher", and in "Parrot Castle II", when Parrot King taught the animals he was teaching the Chinese word for "Hello" was "Ni Hao".
- A written language, not specified to be human, but possibly so, as it was seen in a message written by humans, is seen in Crab Castle. It does not resemble any real-world writing system.