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What did you set as your aim for the interactions between player and NPC? Humor, deeper understanding of the main character, foreshadowing, giving each individual their own unique personality / concerns, or something else entirely?
IMO, all of the above - but that's not a very helpful answer. Lets take a theoretical example of 'Violent Orc Village'. The culture of this village tends toward war, raid and plunder - but this is at odds with the players mission to bring peace to Hippytonia. Luckily there are some in the village who want the endless violence to come to an end, who might be useful allies.
This is the idea which I think the individuals should be framed around. They shouldn't all be the same violent, bloodthirsty caricature though - they should form a web of points of view that build the story of this town. A child who doesn't understand why his father didn't come back from battle, a widowed women trying to rally the women to join in raiding, an injured veteran who hates what his village has become, the merchant profiting off the war. They are all different but they are united under the culture they live under. So these smaller personal stories create a greater web that is your main story. You can even have people who have little to do with the story dotted in there. A girl who wants to grow the biggest, spiciest pepper for example - a fun outlier that makes the town more then 'we may or may not have a violence problem' while still having a link to the wider culture.
I think a lot of what your questioning about character/foreshadowing is down to choice. Is your game a funny game? Is it perhaps missing humour? What foreshadowing do you think is required? But also, I think if your character is oging to interact then every interaction should demonstrate character - because your character will have different views and reactions to these villagers and their ideas. Your peaceloving character may be baffled by the widowed women who wants more violence - or the widower might give the character food for thought. Your character might really help the child who's lost his father or be a little broken by it. All these things build your character and the world.
This is I think my first post on here, so I hope this is helpful and actually what you wanted.