The average human stands on two legs in an upright position compared to most bipedal animals that are either hunched over or use their tails for balance. A human's frontal appendages or arms serve as means to use tools as well as grasp objects, especially with opposable thumbs.
Compared to other apes, humans have larger craniums that hold their brains with their facial features are more aligned with each other including a pair of eyes, eyebrows, a nose, and a mouth. The sides of the head feature a pair of ears for detecting sound waves. Hair grows mostly on the top of a human's head but small amounts of hair grow on a human body over time especially on the face and private areas. Human males tend to have more muscle mass than females who tend to develop more body fat than males including the breasts.
As humans are a species best specialised for intelligence, their physical abilities do not often match up well to other species. The average human's intelligence provides a complex thought process that is tied to both logistics and emotions for problem solving, with rare examples providing varying degrees of processing speeds and memory. They are some of the few species capable of speech and culture and while other species seen in the Devilman series including demons are shown to be as intelligent as humans, they often resort more to instinctive violence and action rather than reason.
However a human's emotional state varies per person as some humans can be pacifistic while others can become violent and unstable. Also due to survival instincts and high amounts of emotions taking over, humans are capable of self-destructive behaviours including the use of excessive force against threats as well perform high vices against others.
These feelings are often taken advantage of by Demons who can take over the bodies of these humans and use their forms to blend into society. Humans that are capable of controlling their emotions and instincts however are able to overpower the corrupting effects of demons and instead take over their bodies and forms to become Devilmen. Also of note is that a very small number of humans are capable of abilities such as psychic powers.
After sealing the demons in the Himalayas, God decided to start over with a new set of creatures, the humans.
The demons break free from the mountain and start merging with humans. However some of the humans retain their personality afterwards, creating devilmen. The demons try to wipe out humanity and reclaim the earth, but the devilmen rise to their defense. Ultimately all three races are obliterated.
After the events of Devilman, God recreated earth and the human race. It is unknown if he used the souls of the previous humans to do so, or if they were placed in Hell like the demons and devilmen. These humans eventually start to mutate into Devil Beasts.
After Dante escapes Hell and bring the souls of the rest of them demons with him, the demons start mass-merging with the humans and the Devil Beasts. Humanity presumably becomes extinct again. The Devilmen and human-aligned Devil Beasts led by the devilman Akira Fudo, join forces with the demons and demon-aligned Devil Beasts, led by the angel Satan to battle God and his angels. The outcome is not revealed.