Now ... since you started this way:
because no actual person in real life, finding themselves in this situation would simply "Trust" that they were not going to be transformed body and soul by this thing that annihilates a person's entire existence, just because ours isn't behaving in the traditional way exactly.
If YOU would read entire post ...
You would find out that i reacted on this with quoting a Wiki ... (i will not quote it again)
That clearly states that within "few hours", "we" no longer exists ... so just the fact that "we" are still there to even wory about ceremorphosis is not matter of "trust", its a factual "proof" that this "thing" is not working for some reason.
You are not providing argument to Niara's line of thinking though. No one claimed that it is not clear that something is off. The fact that tadpoles didn't go off as expected doesn't mean it is safe. If you step on a landmine and it doesn't go off, it doesn't mean it is safe to carry around with you. Therefore:
because no actual person in real life, finding themselves in this situation would simply "Trust" that they were not going to be transformed body and soul by this thing that annihilates a person's entire existence, just because ours isn't behaving in the traditional way exactly.
very early on only Helsin is established as a credible solution.
Is he?
I think so. He is a powerul druid, a leader of the local circle, and studied/studies tadpoled individuals before vanishing. Sounds like a good lead?
Lae'zel, who desperately need get back to her people, is telling you that you should risk your life for her, bcs her people are your only hope ...
Gith also seem like a possibility especially if one plays as Gith. As Mindflayers swarn enemies they could be equipped to combat mindflayers influence as she claims. That said, her being an aggressive alien, I wouldn't be slow to trust her people if roleplaying as any other race. Then of course you meet her "friends" and pursuing this avenue becomes clearly a bad idea. Friendly neighbourhood, tadpole studying elf druid seems like a safer bet (again, perhaps unless you play as Gith yourself).
Gobbo pristess. She is a gobbo to start with, and works for people who want us dead.
There is Auntie and comedic relief guy, but they are more accidental finds that intentional paths to pursue.
which is counter intuitive if one has a potential ticking bomb in their noggins
Depends on lots of things like how big is that bomb, if its even armed, how long it would be ticking, if you are even smart enough to realize danger you are in.
Dont throw away other scenarios as "unrealistic" just bcs *you* (and here i mean YOU not your character) would never even concider it ... if this would be universaly true, we wouldnt have
Darwin Awards.

Har, har, har. Don't switch arguments, Mr. Strawman. Just second ago you claimed that it is perfectly fine to assume that tadpole doesn't present an immediate danger. In addition, it is impossible to do low inteligence runs in BG3, so it is safe to assume that your character has at least a below average inteligence, like myself.
Here is an idea - what if we didn’t know we had tadpole implanted in our head (like so many other True Souls)?
Interesting idea ...
But wouldnt that require complete rework (or erase) of whole tutorial part and several starting conversations? O_o
Even if you would erase it whole and you would wake up on the beach, blessingly unaware of your condition ... why would anyone stick with you? ... why would you be looking for a healer? ... why would you risk your life in Goblin camp? etc. etc.
I thought of it more as a theoretical excercise (akin to
rewriting xxxxx film videos) then an actual suggestion, that said if Larian saw it and thought it would fix all their problem I don't think it would be as difficult to implement as you suggest.
The biggest obstacle is expensive CGI cinematics which would need to be cut or redone, to not include tadpole but other then some rewrites and rerecording would be enough. Perhaps it is still a lot. But maybe then Larian would write something more relatable then "tadpole this and tadpole that".
I think we can wake up as prisoners on Illithyd ship. We are also experiencing strange sideeffects, such as melding our minds with brain-dog and other prisoners and future companions. That something was done to us, is I think enough of a reason to stick together and find out what happened. The fact that we have a tadpole doesn't really change much, I don't think. Finding a healer or someone with magical knowledge would be a priority still. Laez could still want to search for the Creche - something was done to her by Illythids after all.
Then the encounter with dying true soul could be the indicator that we might have a tadpole as well, which could even be dismissed by some companions as we have been feeling better then ever afterall. And by time the diagnosis was made we would be pretty deep into act1, making moonlight tower a more direct objective.
But as I said a thought excerciese more then anything. Difficult to say if and what it would do to the story without knowing more.