If Apple "invented" the GUI by commercializing some ideas that started at Xerox, how is it that the Xerox Star was released before the Lisa? Now, the Macintosh

If Apple "invented" the GUI by commercializing some ideas that started at Xerox, how is it that the Xerox Star was released before the Lisa? Now, the Macintosh was a far more impressive execution of those ideas than either of its predecessors, but to say Apple "invented" the GUI, and to downplay Xerox's contribution, is unfair. I'm not saying this because I'm "invested" in any product or company; I owned a 512-K Mac, I covet my wife's MacBook Plus, but I don't find identification with any particular company's fictional narrative a useful way of discussing technology or history.