AFAIK Excel doesn't show the shape ID in the GUI. It does show the Shape name (not the same thing the ID cannot be changed the name can)
If this is what you need you need to show the selection pane. HOME Tab.. select drop menu (far right in Editing) This will show the name and allow you to rename the picture.
If you really want the ID you can only get it with code
msgbox ActiveWindow.Selection.ShapeRange(1).Id
If you use names you need to be sure noone is going to change them!
PowerPoint has a cool feature "Shape tags" You can add a tag to any shape to identify it. This is ONLY possible in code and the average user cannot change them:
Some info