The Copy shortcut (⌘C) is standard functionality, so no custom shortcut should be needed. (I would delete it.) What is displayed as the shortcut for Copy in the Edit menu, and is the menu option selectable or grayed out when you have this issue?
The second thing is that the shortcut you created is incorrect even though it shouldn't be needed. It needs to be
exactly as it appears in the menu (case-sensitive). So for your example, you need to do "Copy" or "Edit->Copy" to be more specific.
However, a custom Copy shortcut (i.e. ⌃C) won't work in Finder because when you select a file or several files, the text for the Copy menu item changes to something like "Copy Receipt.pdf" or "Copy 3 Items". That doesn't match the "Copy" custom shortcut, and therefore would still use the default ⌘C shortcut.
Here's a guide on how to create custom shortcuts if interested.
On your Mac, assign your own shortcuts to menu commands in any app or in the Finder.
support.apple.com