In the short story by Ray Bradbury, the humans are all dead. They have all died during an atomic explosion. The family had been outside when the atomic blast occurred. All that remains are their silhouettes. 

The entire west face of the house was black, save for five places. Here the silhouette in paint of a man mowing a lawn. Here, as in a photograph, a woman bent to pick flowers. Still farther over, their images burned on wood in one titantic instant, a small boy, hands flung into the air; higher up, the image of thrown ball, and opposite him a girl, hand raised to catch a ball which never came down. The five spots of paint- the man, the woman, the children, the ball - remained.  

This story is set in the future (2026). Technology has advanced to the point that houses are fully animated and are able to accomplish most daily tasks with no human help. This story shows the pros and cons of technology. The house is nearly self-sufficient but the advance of atomic weapons makes it all irrelevant. Even after the humans are gone, the house continues to function according to its programming. It makes breakfast, waters the lawn, reminds the family members (no longer there to hear) about obligations, schedules, and so on. The house "lives on" for a time, oblivious to the fact that its human inhabitants are gone. 

In the poem by Sara Teasdale of the same name, "There Will Come Soft Rains," the events also take place in the future. "There Will" is a phrase that suggests the future. But this could be the near future or decades down the road. Similar to Bradbury's story, the humans are gone and the suggestion is that war has wiped them out. Neither the animals nor "Spring" herself will notice when we (humans) are gone. Any technology and/or civilized progress will be irrelevant. (Bradbury got the title for his story from this poem. The poem is even recited in his story.) 

In the short story "There Will Come Soft Rains," all of the human beings have been killed during an atomic blast, which is why the completely automated home is empty. All that remains of the family is the five white silhouettes of their bodies on the western face of the house. The side of the home is completely black from the intense heat and debris caused by the atomic blast, and the five white silhouettes are the precise spots where the family members disintegrated. The smart home is the only structure standing in a city of rubble and debris, which gives off a radioactive glow at night that can be seen for miles.

Even though every human has died during the nuclear attack, the smart home continues to function flawlessly, as if the family still lived there. The home continues to prepare meals, clean dishes, and issue reminders on its own. In the story, the house is personified and behaves like a human. Eventually, a storm causes a tree to fall on the home, which ignites a fire that destroys the structure. At the end of the story, every human and man-made structure has been destroyed, and all that remains is nature. Bradbury's story examines the dangers of technology and depicts nature as the only enduring force.

In "There Will Come Soft Rains," where are the human beings?

In “There Will Come Soft Rains,” there are no human beings still alive in the story.  As a matter of fact, the only things we see of them are their “painted” shadows on the wall after a nuclear war.  Supposedly, a nuclear blast will imprint the shadow of someone against a wall if they are in a certain radius of the explosion. This phenomenon was first seen with the dropping of the bombs at Nagasaki and Hiroshima.  The only thing still alive (and not for long) is the family dog that somehow survived the catastrophe.  He comes to the door wanting to be let in and fed but, unfortunately, dies.  The robot mice sweep him right up, and he is incinerated in the basement.

It is ironic that the technology that controlled the family’s life and provided them with an easy lifestyle is the very same technology that killed them.  The technology lived on without the family until the very end when fire destroys the last house standing in the city.