Oh, no... don't feel stupid; quite an easy mistake.

And since I did the same thing, I'm happy I could pass along what I learned :)

Gonna take a shot at this because this happened to me the other night

Based on your screenshots here, I think the issue is the placement of folders. The dlc, heroes and trinkets folders (as well as the preview_icon.png picture if you're using one) should all be inside the data folder as a root level.

I just completely forgot to put a 'data' folder on my first attempt, but adding that cleared everything up for me :)