Hey,
I noticed that most, if not all artwork is of one person or thing. Can you create art works with more than including backgrounds with ZBrush?
If so, do I need another 3d art software for indoor and outdoor scenes.
Still learning…
CD (UK) 
Zbrush was originally created as an illustration application, and “scenes” are quite possible. But they tend to be done more with 2.5D compositing than one big real time 3d scene. For that sort of thing people tend to work in more traditional 3d programs with raytracing rendering engines, and they use Zbrush to sculpt and detail the objects in that scene