Most NPCs do nothing yet. However, brawlers can be brawled with to gain 1-5 XP per fight, medics can heal you for a few hundred credits (useful right now if you want to be able to brawl repeatedly, before you level up a bit and have more HP), and workers and builders work in factories for production factions and can be used to construct facilities if you have money and raw materials.
Raw materials are used in factories by production factions to produce ships, vehicles, droids, items, etc. and are also used by factions or individuals to construct new buildings if you have money and a place to build.