Humans are a sentient race living in the City. Many pivotal characters featured in BLAME! are humans.
Biology and Appearance
Humans in BLAME! appear very similar to real-world humans. However, millennia of separation between groups of humans have led to the evolution of highly different "breeds."
Humans of the City adapt to their environment, physically and mentally. The Planters of Bio-Electric Company (pictured right) stand on average nearly twice as tall as an individual Killy's height. In contrast, the Electrofishers are all significantly shorter than Killy. The humans Sanakan was hunting before she was found by Killy and Cibo were presumably even shorter, as Sanakan barely reached Killy's chest in height.
The term "human" itself is used rather loosely; both Killy and Dhomochevsky, who were provisional Safeguards, are classified as humans. The same can be said of Cibo who, despite being born as a human, reincarnated herself several times into bodies that were not. Thus, any humanoid creature that is not a Silicon Life, Builder, or full Safeguard can be classified as human. In addition, most humans have at least some cybernetic augmentation, such as the non-functioning but present retinal displays of the Technomads. The same can be said of Killy's hip connector and Cibo's wires.
Culture
Thousands of years of separation between the Strata have caused each Stratum's human population to develop their own, if not similar, cultures. The Planters, for instance, have effectively been slaves to the President of Bio-Electric Company for centuries, as they have been since Cibo was alive and presumably long before. It is not known whether Cibo herself was a slave, but this is unlikely as she was not a Planter.
In contrast, groups such as the Electrofishers and Technomads exhibit warrior cultures, unabashed by death at the hands of the Safeguard and actively fighting against them when searching for supplies outside of their shelter.
Perhaps the most "successful" society of humans was that living inside of Toha Heavy Industries before its forwarding. The only member of this culture seen was Seu, a tall and powerfully built human capable of fighting off Ivy and Maeve simultaneously with what appeared to be a normal longsword. It can be assumed that, since Seu held the Net Terminal Gene, the other humans of Toha (or at least the Eighth Cave) also held the Gene. However, they all died instantly when Toha was forwarded outside the City.