"What do you want? Who Are You? Where are you going from here?" - arc questions from Babylon 5
The Role of PC - Planetary Citizens
From the point of designing the game, are like romanticized pirates of the 18th century Caribbean Sea.
Consider the whole world to be an ocean. Each city state is a nation fighting for trade lanes and resources. Reanamates are the natural hazards of the sea - type ones are like shoals to be navigated around, Type Two hidden sandbars hard to find, yet waiting to wreck. and type Threes are vicious storms that can tear travelers apart. Citizens are pirates on these waters - hunted by the nations, fighting amongst each other, and suffering form the reanimates as well, but in the end- an intelligent threat.
Within the game universe, they're homesteaders trying to make the best of the area they've immigrated too. After a long and uncertain journey, they've arrived at what seems like a lush paradise. However is already crawling with pesky natives that do not like the citizens presence.
Citizens are not always hostile to humans. Sometimes they're willing to trade objects picked up in their travels for food or raw materials. Mineral wealth like iron, steel, and rare earth elements are the most sought - setting up mines and the means to process the ores takes quite a bit of time.
Even when they are antagonistic, its not always malicious. Citizens will often raze old ruins to claim new territory or eliminate reanimates - but they give warning prior so people can evacuate. Most of the creatures piloting alien war machines are uninterested in maximizing casualties. Some are professional soldiers from the Mercenary Guild Family that see limiting collateral damage as part of their job. Others are newly recruited conscripts with little interest in fighting.