Human life is the state of being a human and being alive, as opposed to being a human who was formerly alive, but is now dead.

All the human life that we (humans) know about exists on the Earth, specifically the land parts rather than the bits covered with water.

Thus far, all humans start off by being alive (the start of this state is known as "birth"), then carry on being alive for a while, doing various stuff, but all of them finally succumb to the process known as death, following which they are dead. The bit where they are alive is called the "human lifespan" and the stuff they do while being alive is sometimes known as the "Game of Life".