iPhone 6+ Deleting Photos does not release memory
iOS 8 and newer has a feature called Recently Deleted in Photos. 

Try opening photos then tapping on albums. Now tap recently deleted then press select in the top right corner and press delete all. 

This should release all of the old photos. As regards to deleting all of the misc. data, you should be able to download an app on your computer like iFunbox or iExplorer to use (part) of the iOS filesystem. 

With this being said, you should be able to open the Application Archives folder and delete all of the zip files found there.