Starfield's central story has you siding with Constellation and discovering the mysteries of the artifacts and how they tie to the greater secrets of the universe. Continuing through the main story will bring the player closer to the Starborn and the unique NPCs who are Starborn.
Starfield: Who Is The Emissary
The Emissary is a Starborn who becomes a major NPC towards the end of Starfield's main story; here's who they are beneath the mast.