Humans in Buddhism (Sanskrit manuṣya, Pali manussa) are the subjects of an extensive commentarial literature that examines the nature and qualities of a human life from the point of view of humans' ability to achieve enlightenment. In Buddhism, humans are just one type of sentient being, that is a being with a mindstream.
In Buddhism, humans have a very special status: only a human can attain enlightenment as a fully enlightened Buddha. Enlightenment as an arhat can be attained from the realms of the Śuddhāvāsa deities. A bodhisattva can appear in many different types of lives, for instance as an animal or as a deva. Buddhas, however, are always human.
The status of life as a human, at first is seen as very important. In the hierarchy of Buddhist cosmology it is low but not entirely at the bottom. It is not intrinsically marked by extremes of happiness or suffering, but all the states of consciousness in the universe, from hellish suffering to divine joy to serene tranquility can be experienced within the human world.
Humans can be seen as highly favored, in that they have an immediate reason to seek out the Dharma and yet also have the means to listen to it and follow it. Among the lower realms, Pretas (aka hungry ghosts), and dwellers in the Narakas (Buddhist hell(s)) are gripped by pain and fear, and can only endure their lot but cannot better themselves. Animals are intellectually unable to understand the Dharma in full. The way of life of the Asuras is dominated by violence and antithetical to the teachings of the Dharma. Most of the Brahmas and Devas simply enjoy reaping the fruits of their past actions and think that they are immortal and forever to be happy and so they don't try to practice the Dharma. When their past karmas have all had their result, these devas will fall into lower worlds and suffer again. The lowest sorts of devas deal with strife, love, and loss just as humans do, but even so they lack the spur of imminent mortality that can lead humans to seek, not merely a better future life, but an escape from saṃsāra altogether. However, there are stories of beings in these realms deciding to practice and reaching enlightenment.