So are you disputing the part that the Xerox product was graphical? Or that it was a user interface? In what possible definition that you've contrived in your mind does what I just linked you not qualify as a GUI?
The Apple II came with video built in. It also had a user interface in the form of a command line. Thus, when people used the computer, graphics were drawn on the screen, sometimes in the form of pictures (such as for games) and sometimes in the form of glyphs and even icons, to represent concepts to the user of the command line. Your position implies you believe this to be a "Graphical User Interface".
The problem here is that you're discounting that these things are incremntal in nature and saying the invention happened at Apple.
Where does the GUI start? At the ncurses-like menu-driven interface? At the point where this interface gains more than two colors? At the point where there are icons? When there is a menu? When there is a paint-like drawing tool? When there is an apple logo on it?
Some draw that line at Xerox, you draw that line a bit later and attribute the "ground-breaking invention" of a GUI to Apple.
I don't see it either way, they are all refinements along the continuim from the command-line to the GUIs we have today.
Apple happened to hit the mix that a large number of people grew to embrace and some attribute all that came before as garbage and the win to Apple. Which I think is extremely misguided, but what can you do but shrug it off.
I honestly can't tell if you're trolling or not.