Launch applications (which might create new windows). Switch between windows. Close windows.
That sounds like the people who grew up using nothing but a smartphone all their lives. I find that there's an entire new generation of developers (and likely users) who don't understand basic window management at all --- all they have on their huge monitors all the time is one maximised application. Meanwhile I have several dozen windows open, all of various sizes, and when they see it, they are surprised at how I can work in such an environment.
No, I would not consider something that can't do what even Windows 1.0 could (tiled, nonoverlapping windows) a "window manager".