Thanks.
No, none of these were any images I want.
I don't have a desktop image, just a plain black desktop. Years ago I used to do fancy things on the desktop, but I decided clean was better and black made the few icons I have on the desktop stand out better.
I made a disk image, put the 2800 images in the recycle bin, the world didn't end, the computer didn't explode, and Bill Gates didn't show up at my door.
So if in a week or so nothing is asking for one of those images, I'll empty the bin.
Notes