Your companions and their fantastical backstories are quite frankly ridiculous. Could I believe these people existed, sure. Could I believe these people just so happened to be in the same predicament, in the same place AND at the same time? No, why? Because my brain is telling me on an unconsious level these characters are there for the sake of the story not because of it. At this point my brain becomes aware of these anomalies and switches off.
The game world, story and character motivations break rule 1. <<<< This is the story and as such is objectively shite.
Because *your* brain can't figure out why these characters are there together means the story is objectively bad? Objectively. As in: not influenced by personal feelings or opinions, but only representing facts.
lol
Okay.
Hmm.
Shadowheart is there because she was chasing an artifact. So we know why she was there.
Lae'zel is a Githyanki. The artifact is covered in Githyanki symbols, and Githyanki are chasing the Nautiloid. Maybe Lae'zel got caught when the Mind Flayers raided some Githyanki to get their hands on the artifact? Gosh, suddenly it's feeling more reasonable that Lae'zel is there.
Wyll has a pact with Mizora, and she's been kidnapped away to Moonrise Towers. Maybe he was captured as a bystander because they had reason to get Mizora? Sounds like Wyll's reason for being there makes sense.
Gale? He has a condition based on Netherese magic, and whatever's putting the tadpoles in stasis is Netherese in origin, so maybe there's a connection there somewhere?
Astarion? Maybe he was just captured. Maybe Cazador traded him in some kind of bargain, and maybe that has something to do with the infernal tattoo on his back?
The point is, we're in early release, in act one, and because you can't figure out why all the characters are there, you immediately assume everything is objectively bad.
This is not objectivity. This is your subjective opinion. There's a big difference.
As for understanding why all these characters are in the same predicament, I think that's going to become more and more clear as the story unfolds. There are already hints all over the place.
