I think you’re doing alright so far, I wouldn’t think too much about it, especially since you’re not doing anything wrong. The main thing above all else that draws people in is how your image looks at a thumbnail size. If the sex appeal is still clear and very easy to see then users who come across it who are looking for porn will probably click on it instinctively to have a closer look.
As for why your animations are the most popular images, that also just relates to just how attractive your image is at a thumbnail size. It’s hard to miss something that’s literally a moving picture among other pictures that are just sitting still, especially when there’s a butt right up against the camera. Only exception to that is if the user is specifically searching for animations, in which case that’s all that they will see.
@d1ckbitch
The picture has to convey a meaning, something strong enough to catch people’s heart. Consider an artwork about two completely random ponies having a sexual intercourse. It’ll get a few upvotes because, you know, it’s porn, and not a bad picture. Now recolor the horses to turn them into a Mane 6 and a Mane 6’s parent, and add some speech bubbles implying incest is rampant in the family, and see what happens. The picture barely changed, of course.
I’d say that’s not really giving more meaning to a picture and is more along the lines of just catering to a common fetish that is searched for quite often but you still get the point across.