Celestials and More

Of course, as James Gunn said, the presence of the Watchers also signified that the Marvel Cinematic Universe is gradually becoming the Marvel Cosmic Cinematic Universe. So the Watchers (who collected all the knowledge in the universe) foreshadowed the introduction of additional alien species.

Ego, as a Celestial, represented one of these species. And he wasn’t the only Celestial out there. The Grandmaster and the Collector were just two of the Elders of the Universe, and Eternity was mentioned for a second time in Guardians of the Galaxy: Vol. 2. Based on these characters, we feel safe in saying that this movie marked the beginning of the cosmic expansion.

If we add Ego’s flower (you know, the one that threatens to destroy Earth), we can say that the MCU isn’t just cosmic, especially if we regard it as a consequence of Strange’s use of the Time Stone rather than as plot-hole. We can even add that alternate timelines have been established.

Sure, this is just the beginning of a theory, but it sounds great to us!