My wallpaper is just plain reddish brown with no features at all. Features on wallpaper would just distract me and make some of the desktop shortcuts harder to see. So no people, no animals, nothing. I chose reddish brown in the faint hope that it would be less likely to keep me awake if I'd been using my computer before going to bed, since I don't want to stop using my computer just because bedtime is coming up.
I've never understood why people bother with wallpaper, so I looked it up. Apparently they do it to "personalise" the computer, to express their personality (in my case I know it's my computer and don't need such reassurance of the fact - to make it my own I use a variety of technical gambits to defeat Microsoft's continual attempts to make it their computer, and to get things so that I can get the results I want with the minimum of fuss and bother). They also just like a particular picture (in my case pictures soon become invisible if I see them often), or they get off on inspirational pictures or quotes (in my case inspirational stuff like that does little or nothing for me), or they may have a picture of a loved one to make them feel more comfortable (doesn't work on me, I know it's only a picture). In other cases they use wallpapers to help organise their work - that seems a lot more up my street but I don't know how that would work, and I can't imagine anything of that kind that would be an improvement on the desktop shortcuts I use. It seems I'm as "heartless" as Mr. Spock when it comes to computer wallpaper. It'll be interesting to see whether most Aspies here have similar views to mine or not.
But I don't look upon wallpaper users with disdain. Some of their wallpaper photos are very impressive, just that if I had to look at them every day they'd soon become invisible to me.