The bless and curse of letting artists crop their own thumbnails / image previews in a gallery.
It can be nice for choosing an appealing part of your art (and crop off empty areas for example), to make (small) parts of your art easier visible in the little thumbnails, or to hide adult parts of a picture.
A lot of artists obviously don’t think much about cropping their thumbnails. Often they always pick a head shot - no matter if it’s a badge, an icon, a comic, or a complex picture. Often you have no idea why you should click another head shot thumbnail - and miss a nice complex picture behind it. Sometimes thumbnails are picked that badly, that you have no idea what it is at all.
Please, when you create those thumbnails (like some galleries offer you) - do it reasonably. Choose a preview that actually shows the viewer what’s on the picture. Otherwise there won’t be much motivation for a viewer to click on it. You know what’s behind, others don’t. I know it’s hard sometimes, especially when your picture is a different format (e.g. much wider than high) than the square icon, but it will make browsing galleries a lot nicer. :)