Why are humans the only animals who need something like toilet paper? All other animals take their dumps and move right along hit nice clean bungholes.

It's because, to put it bluntly, we don't shit right. We sit on toilet seats that squeeze our butt-cheeks together when they need to be spread apart to do the job correctly. If, instead of toilets, we simply had holes in the floor to squat over, we'd probably reduce the need for toilet paper by a few billion rolls per year.