system
A chat on subreddit /r/pcmasterrace
human
If you genuinely don't remember even having this picture on your PC, I'd recommend wiping all your drives and reinstalling windows. There is obviously something on your PC which you didn't do and I personally would not like that at all.

(Make back-ups obviously.)
gpt
Usually it's software bugs and there is an explanation. OP for example has Eminem tracks with album covers on his PC.

My background has also changed itself after an update. I made an GitHub issue and it got confirmed it was a bug by the devs themselves.