That last one is quite nice indeed. However, be careful when claiming something is under the CC0. It is NOT explicitly said there that the author put it under CC0. On the contrary, one can read:
"Visitors: The wallpaper is available for download (free) only as background on personal tablets, smartphones and desktops. Do NOT upload on other sites or use in other purposes without Richard's permission!"
First of all, the 'free' is ambiguous: free in what respect? Free as in beer or as in speech? We're (maybe) incorporating it INTO an OS, and distribute it that way; it's more than just using it as a personal wallpaper on your own computer, thus.
I'm afraid I can't use that for the vote. I'll rather be a bit strict than not strict enough, otherwise z98 will chastise me anyway.
The other may well qualify, I didn't check them all out, but I'm not planning to load whole galleries; I expect people to do a preliminary choice of what they like the most in the first place, as potential candidates. Otherwise, as you say, it would be overwhelming if it's just copy/paste whole image-galleries.