With the growing number of files you will get a bigger problem searching and organizing all the files on this website.
You *could* create more categories but it has a lot of problems.
You should consider allowing the author (and maybe even the users) to tag files based on their type, effect, trigger, target audience, if it is a free or pay file, and most important of all: it's contents.
It will allow people to either make a personal list of tags that interest them and/or a list of tags that doesn't so they don't show up when you look around.
For example if you aren't interested in furry, diaper or feminization files you could then have an option to hide them (at least temporarily).
Worth the trouble? On a sidenote Gmail chose the 'tagged' approach as well as it is far superior to the typical 'folder' structure of other email clients.