Bunch of random thoughts and suggestions incoming.

You describe a setting but not a campaign. “You’re adventurers going into a mysterious desert. Because adventure.”

I’m guessing you have plans for what’s out in the mysterious and foreboding desert, but a big part of getting players invested is giving their characters a reason to be there. Something more specific than “I sense adventure that-a-way!” Especially when advertising a game. This description suggests to me a lot of exploration and fighting random monsters. But I may be way off because while some anticipation of the unknown is good, undefined mystery as a campaign hook doesn’t give anybody a clue what the game will actually be like.

And if you’re planning to sandbox it and just pull stuff out of your ass in reaction to whatever the players do you should make that clear immediately. First thing. Some people love that sort of game and some people hate it. Personally I’m in the latter and nothing is worse than expecting to be presented with an adventure and at least some clues and hints to start from only to get, “So, uh, big desert! Very mysterious and shit. What do you do?”

Caravans are trading expeditions. It isn’t good business to just wander into unknown and presumably dangerous territory with a bunch of valuable goods unless you know someone is out there who wants to buy your stuff. You send an exploratory expedition first to discover these things, because for all we know the previous groups just aimlessly wandered into the desert and got eaten by giant sandworms or something.

An exploratory expedition would typically be smaller than “a village” and only need a few skill sets who are there for very specific and clear reasons. A couple diplomats and negotiators to make diplomatic and trading arrangements, some surveyors and cartographers to make maps so the places are no longer uncharted, and some scout and soldier types to protect them. That last part is your adventurers. Considering previous expeditions have gone missing it would seem prudent to send along a larger fighting force because something has clearly prevented those groups from returning.

An issue with a large expedition is the party getting swallowed up by it. They could specifically be scouts, moving ahead and investigating those weird looking caves over there or such (and allowing the party to act independently to perform narratively important tasks), but this is a specific focus and not a vague “people of various professions who are there for their own reasons.” Most players don’t make a wizard, barbarian, or paladin because they want to be a random craftsman in a town. Anything in their backstory to that effect is exactly that. Backstory. Setup. Stuff that happened before they became a cool adventurer. Cover that as much as you want in RP discussion, flashbacks, or as part of the character’s initial introduction but make clear what the party will actually be doing in the campaign so players can prepare appropriate characters.

If the idea of a mobile village is important to what you want to do with your campaign then you need a good reason for bakers, blacksmiths, and textile weavers to be wandering off into unknown and presumably hostile territory. Off the top of my head the two things immediately coming to mind are a nomadic community or a large number of refugees looking for a new place to settle after losing their homes in some sort of war/calamity/etc. Both would still need scouts, outriders, and guards as they venture into unknown territory, which is where people with class levels come in, either as part of the original group, hired on, or joining for their own reasons of adventure, altruism, or fleeing something themselves.