In Guardians of the Galaxy 2, Ego gives a speech wherein he talks about his origins and his search for meaning, illustrated with a cool claymation-like diorama.
I don't know where I came from exactly. First thing I remember is flickering adrift in the cosmos, utterly and entirely alone. Over millions of years I learned to control the molecules around me. I grew smarter and stronger. And I continued building from there, layer by layer, the very planet you walk on now.
But I wanted more. I desired meaning. "There must be some life out there in the universe besides just me," I thought. And so, I set myself the task of finding it. I created what I imagined biological life to be like, down to the most minute detail.
The diorama shows the creation of Ego's human avatar.
I wanted to experience what it truly meant to be human as I set out amongst the stars, until I found what I sought. Life. I was not alone in the universe after all.
How could Ego have so precisely guessed what biological life was like, much less what a human is, before he has ever encountered a single other life form?