I rename files as I download them (or copy them from my phone/camera) or I just remember the file name that I downloaded. I suppose it's a problem if you have to deal with many unnamed images, but if it really came down to that I would just open up nautilus.
There can't be a more classical linux/developer response to a serious UI issue than "I just do this other repetitive manual task to solve the problem, don't see what the big deal is."
grand-canyon-001.jpg grand-canyon-002.jpg grand-canyon-003.jpg grand-canyon-004.jpg … grand-canyon-991.jpg
Or maybe
grand-canyon-east.jpg grand-canyon-west.jpg grand-canyon-north.jpg grand-canyon-south.jpg … grand-canyon-northeast.jpg
Thumbnails solve real problems and other guis have had this as a completely solved problem since literally the mid-nineties.