How to work with filled paths?

Hi all,

I've got several asset packages from various marketplaces. I've noticed that many of the .ai shapes and objects aren't paths but instead are filled paths. For instance, let's say one is a ribbon. I'm unable to fill the ribbon because the object is the stroke itself, not the ribbon. Why do folks do this, and how on earth am I supposed to work with it? I've researched off and on for months, and played with various files over and over, but I'm out of ideas. Short of locking the layer and using it as a pattern to redraw the object myself, I can't figure out to use all these shapes. 

It feels like this is a basic question I should know the answer to, but here we are. I'm a Photoshopper who is still shakey with Illustrator, so I'd appreciate someone clueing me in.

Thanks for any insight you can give!

-JoAnne