On your adventure in Port APICO you'll come across a whole host of NPC friends that will help and encourage you on your journey!
NPCs act as a source of lore, but also as shops where you can buy things. As you progress in the game different NPCs will comment on your progress, and let you buy more useful and advanced items!
All NPCs except for Nana Beelia, Ellraiser, and Metakitkat have shops - the shops contain different items based on the NPC, for example Beetrix will sell carpentry and crafting related items.
Like all menu objects, NPCs can actually be picked up with a to be moved to other places (except for Ellraiser, Metakitkat, Moth(ense) and the Merchant)
These are NPCs not specific to a single biome.