Using nothing but what you've said, I imagine your stories not unlike the book World War Z (I'm sad I have to make that distinction). If you haven't had the pleasure of reading it, they're basically self-contained stories that are told in chronological order. I imagine a great deal of stories could be told via the trading hub. Tales passed on by salty old smugglers or young hotshot pilots, told to anyone who would listen. Maybe some shady backdoor deals or hushed whispers of assassinations or "disappearances." Robots or AI could rebel. Pretty trope-y but hey, it's there. You could go with something along the lines of emerging AI bounty hunters or traders. Their take on a situation could be vastly different than a human's. I'm in agreement with CraigEllsworth. Build around your focus. If it's short stories a la World War Z, then making each story engaging in its own way should be the focus. If that story is heavily about characters, then build the characters first. If it's more about a broader situation like "Smugglers vs Police" or "Zealots vs Technocrats" or whatever, then building the feeling of conflict would take precedence over individual struggles, though you could highlight those as well. Just my two cents. Hope it made sense, since I'm just spouting nonsense.