caravans

Transportation of Necessities - caravans that move water, food, stone or other important supplies between cities. Usually under the direct authority of a city.
Scavengers - caravans that seek out recent worldfalls to get whatever valuables they can from them, either to use for themselves or to trade for vital supplies. Usually independently owned.
Tamers - caravans that seek out creatures that have recently worldfallen. Ideally livestock creatures, or those that can be tamed as beasts of burden or as pets. Trades captured beasts with farming communities for vital supplies. Also likely to keep some livestock for themselves to be at least a little bit self-sufficient.
Crafting - caravans staffed mostly by those who can craft items (for example blacksmiths, alchemists, carpenters etc) who trade those items for vital supplies. Most people living in the big cities don’t need these caravans, but those living at smaller outposts find their services very valuable. Usually independently owned.
Protection - caravans that seek out and defeat dangerous wildlife threatening the smaller outposts. Usually operate with an implicit understanding that their services are paid for in vital supplies. Can be independently owned or run under the direct authority of a city or other organization.
Research - very uncommon - caravans that travel Debris looking for important data on the nature of the world and the worldfalls. Probably staffed by magic users, who trade uses of their spells for vital supplies. Operate usually under the direct authority of a city or organization.
Entertainment - caravans that put on some kind of performance for a fee of vital supplies. Including things like gladiatorial combat, theatre productions, musical performances etc.
Mail delivery - very small caravans (probably only a driver and a bodyguard) that deliver written correspondence and packages between cities, outposts or to individuals. Operate under the direct authority of a mail company of some kind.
Transportation - caravans that transport people across the treacherous surface of Debris. Many of the other types of caravan listed will charge a fee and offer this service for those interested.
Medical - caravans that travel between smaller outposts and provide medical care and aid to those who live there. Usually independently owned or possibly under the control of an organization.
Educational - similar to medical caravans above, travel between smaller outposts providing education to kids who don’t have access to the larger cities.
Religious - caravans that seek to spread the word of their god. Independently owned or under the direct control of an organization or potentially their god.
Military - caravans that serve as a military force for the organization or city that runs them.