Android system takes about 12 if that helps and cached data takes up another 2 on my phone as well. Samsung may use more with all their optimizations & addons. But you should see that listed too.
If you scroll down there should be an Explore option so you can go thru the various folders. I didnt realize that i have photo on my internal memory. I need to move those to my SD card so they get backed up with the rest.