Ok, that's fine, I'll agree that story has to be about people. I'm not sure what you're referring to though? Are you looking for more discussion of galactic politics? Are you looking for description of a space farer's lifestyle? Are you looking for NPC stats? What are you looking for?
People are people though. I don't need to explain what a human is obviously. The difference from people in the game and people now a days is mostly the technology that's available. If anything a setting is telling you what's different and the technology is a main part of the setting. Science Fiction is about the effect science and technology has on people.
Maybe there's something that seems obvious to me that isn't coming through in the text to you. For the most part, an average NPC is simple to stat out. 2d is all you need for a non-descript person. For a more specialized NPC, add traits that match their function in the story/game. Maybe a more detailed description of how to do that is what you're looking for?