We’ve seen the Celestials Before
This won’t be a huge surprise to everyone, but it is a nice tie in. Though Eternals is the first time in the MCU that it’s defined who the Celestials really are, what they do, and their role in the galaxy, it’s not the first time we’ve seen one. Knowhere, the place the Guardians of the Galaxy first visit in their first film to meet The Collector, exists inside the head of a fallen Celestial, and we see glimpses of them during the Collector’s explanation of the Infinity Stones’ powers. Marvel knew they’d come back to the powerful beings years ago.
