This first photo is fairly straightforward. A solitary figure adds balance to the scene (the globes of the lighting fixture grab most of the attention), aids in giving depth to the space and shows the sliding glass wall in action.
A similar thing happens in this photo, but with a dog. Yes, even a pooch can help photos. This one draws our attention outside, away from the huge fireplace that dominates the sparse interior. The dog's distant gaze lets us know that the view is more expansive when seen from the porch.
Kitchens are popular spots for inserting people into photos, probably because they embody more action than just sitting around. Also, in an open plans, the kitchen is the nexus of daily life where people are at ease. In this modern house in Montreal, the mom and daughter humanize what many people may see as a sterile space.
The woman in this photo, on the other hand, shows how a kitchen can be a flexible space used for tasks such as computing. Again, having a dog in the photo is a great touch.
I love the way people are used in various photos in this Japanese house. Three bodies are visible in this shot, vertically stacked yet each in a different space. Their placement is compositional, but it makes the complexity of the house apparent.
In this view, the child on the left occupies the same position as the top person in the previous photo. Both look out a triangular window that follows the line of the roof above the hallway. The placement of the mother and son in this photo also leads our eye, directing us toward what is important. (They also make up for the lack of furnishings.)
This space may need some furniture too, but we don't think about that with the dog sitting in the middle of the floor.
Not sure that the wall on the right is for climbing? The person falling from the top makes it as clear as the glass behind him.
Stairs are static entities that imply movement, but adding a person makes that movement tangible (note the slight blur). The addition of the figures also softens the space between the concrete and glass, amplifies the openness of the stairs and accentuates the reflectivity of the glass.
This is one of my favorite dog photos on Houzz, because it shows design tailored just for canines. The outdoor shower cleans off messy paws and fur, and the small opening in the wall lets the dogs enter and exit the house at their own will.