Yeah, I'm gonna back you up on that one. Sometimes assembling the group in session 0 is what's right for the story, and sometimes it really, really isn't. Think about how many movies literally have "Assembling the team" as almost their entire plot. The Avengers hangs two hours of non-stop action on "We need to put a party together." Every heist movie is basically required to have a "Assembling the team" sequence. Session 0 is where you lay out the expectations of the game, and your players think about either how their characters have already interacted, or how they will interact when they eventually meet. You give people an idea of what they're getting into, you pitch the tone and the style of the game, and you help people shape characters around that. As an example a friend of mine always pitches his games by describing who they would be directed by. I remember vividly his "Lock, Stock and Two Smoking Halflings" game, a Warhammer Fantasy Roleplay If It Was Directed By Guy Ritchie experience. Just setting that sense of tone up front meant that we all knew to make characters who would fit the vibe. I played "Blackhand Seth, The Scummiest Elf You've Ever Met," one part Brad Pitt Pikey, one part Jack Sparrow, and I had a blast. In my most recent campaign I'm running a Shadowrun game where the group would be assembled in session 1 by a down on his luck fixer. My pitch to the players was simple; make fuck-ups. I wanted characters who were at the end of their rope, lacking in options, either so green no one would trust them or so tainted by past failures that no one wanted them. The kind of people who would take a job from a fixer who had burned every other bridge. They rose to the assignment beautifully, and by four sessions in the group has already formed some absolutely fascinating relationship dynamics. A lot of that has been shaped by their first experiences together, figuring out how to work as a team, sometimes distrusting each other, and slowly discovering reasons to care about each other.

There are options besides "strangers meet in a tavern and awkwardly introduce themselves" and pre-made perfectly-tailored party. I'm a fan of starting in media res, with the characters all in a location for their own reasons, when shit happens that forces them to act as a group. I've just recently started the video game Baldur's Gate 3, and it's not a bad example of what I mean.

"Strangers meet in a tavern and awkwardly introduce themselves" is just an example of "random group forced to team up". I've tried the whole "use McGuffin to literally force the party to work together" and still get roadblocked by that one inevitable player who insists on being the "edgy loner who has to be dragged into everything". Yes, even with the threat of death, they usually just waste time trying to argue how "that's what [their] character would do! [I'm] just punishing [them] for playing [their] character! Reee!" Still, on another point, players will still have to do the whole rigamarole of character introductions that always feels like the first day at school unless the characters were made together during session 0 anyway. I just nip all of that in the bud by just eliminating that from my table through the previously stated method: starting in media res with a party that has been pre-established during session 0. BG3 works because the cast of characters are all pre-written, specifically designed to work with that story, being that it is a video game. Real players, unfortunately unless you find a unicorn, do not roleplay on the level of professionally hand-crafted characters.

"Oh, you encounter a desert. There's nothing around for miles"

What if they leave the party and create a new character to join the party that fits in better? Is that good or bad?

I mean, it's good, but it feels like an over reaction. They don't need to make an entirely new character, they just need to think of a reason they'd cooperate. It can be a contrived reason, that's fine, but they need to work together. Some examples, 1. Highly shy character "warms up" to at least one other character and sort of talks to the group "through" that character, but you can still (as a player) face the whole table to talk as a group. 2. Character who is extremely distrusting has met a character before (just tweak backstory) or finds at least one other character implicitly trust worthy. Maybe the Rogue who has been backstabbed too many times trusts the Paladin because they know they're too honest to lie.

It goes for the players among each other too. It's not just the one character in OP that dislikes or distrusts the party. It's up to the rest of the party to also accomodate them. If you have a moral character in the group you might refrain from murdering, raping and pillaging for shits and giggles. As they say "the only way to have a friend is to be one".

Everybody plays RPGs differently, but it's funny how some people don't get the term "roleplaying" and are constantly, relentlessly playing their real selves in the game.

I'm new to my party and roleplaying in general (though I've consumed it as entertainment) and I'm having a slightly different issue. My character was intentionally designed to be a bit naive to match me as a player, and doesn't have high skills in any int based stuff (at least for now) and instead has medical, nature, survival, etc. A lot of puzzles or traps etc I can as a player try to reason through, but my character shouldn't be able to sus out, and I feel torn between playing the character as it should be or adding ideas to solve stuff so we aren't just sitting there twiddling our thumbs for ideas.

Fun fact: The Expanse books (and eventual TV show) were started as a unique role-playing campaign where the person running it (Ty Franks) would write a prompt, the players would explain their character's reactions. He'd then write a story section incorporating that and the players would say how they reacted and so on. There was a core group of characters who were the "survivors" early on, but one of the players had to drop out early-ish, so in the next bit of story that character died. That was carried into the books and TV show, which is why after the core group of characters is established, there's a sudden, shocking death.

Wow that really is a fun fact!

Sometimes it's hard to distinguish between factual knowledge and just cleverness. There's no reason a bumpkin fresh off the farm can't be curious about what makes something tick, so they look under it or break it open - and whaddya know, they find a hidden thing. It's really up to the DM to say no, your character wouldn't know to do that.

It's natural that we gravitate towards familiarity. Case in point, how some actors always seem to play the same character, no matter which movie they're in.

Yeah that's a good parallel. Lately I've been watching Kaitlin Olson's show High Potential. Even though she's playing a super-smart crime solver, to me it's the same character she played in It's Always Sunny and The Mick.

Maybe your char bumbles around the room doing goofy things instead of working hard and logically to crack the puzzle and the dm can make your bumbling uncover extra clues that advance the plot.

If you don’t have a reason to work with the group, accept that this is a one-shot for you, which may be retcon’d as needed.

Also accept that you suck at making characters

I mean, I think they get the term, but just have a hard time doing it.

"I perform a history check to see if there's any historical significance about this desert."

DM: As you walk away, you feel a slight tingle in the air before a flash as bright as a thousand suns blinds you for an instant before... nothing. A bolt of lightning has vaporized your body. Miraculously, nobody else in the vicinity seems to have been harmed in any way nor even do they seem to have noticed what just happened, including the fact that you just disappeared. It's as if the Gods themselves, for no particular reason, have arbitrarily decided to smite you out of existence entirely. Ready to roll a new character?