I confess to being confused, so what I say here may be of no help.
I am not sure what you mean by "shelf". Do you mean CC's cover view, like this?
Or do you mean CC's list view, like this?
If you are seeing the list view and want the cover view then you must tap the "cover view" icon on the action bar (the 4 small squares marked in the second image).
From what you say I suspect that you are using the Cloud Connection with Dropbox. The Cloud Connection supports a hierarchical list view of books. In this connection the only thing you can do with a book is download it to CC's library so it will appear in the two views shown above. You download by long-pressing on a book, by tapping to get book details then choosing "Download", or by selecting the "Download all" menu option to get all the books in a category. Once you have downloaded as many books as you wish then you "Disconnect", which will take you to CC's library manager, where you can use the cover or list views. You can use the grouping drawer to select subsets of books. And you can launch a reader app.
If you want to browse Dropbox using a cover view then CC isn't your app. The reason: CC is designed to be offline as much as possible so it can be used when roaming or somewhere that has no service at all. It goes online only when you ask, using one of the connection types, in order to put books into its offline library. While online it uses a "tree" view, which seems to be what you are describing. Other apps stay online permanently and can show dropbox libraries in a cover view. If you bought the wrong app then
you can ask for a refund.
As for having a "huge" library: many people keep their entire library in CC, where the "entire library" is thousands of books. The largest library we have seen is some 35,000 books. Many people have libraries of around 10,000 books.