This isn't your typical "I start out as a farmer and take up adventuring as a profession after the dragon ate my flock" sort of story. All of the pre-rolled characters have a decent backstory that seems to indicate that they've been doing this a while. You can't tell me that in the 200 years since Astarion was turned into a vampire that he didn't pick up more than the basics of picking locks. Even worse is the thought that Gale was wandering the planes but still can't cast more than a couple of level 1 spells.
Maybe start out at level 5 or something like that. Makes it a bit more plausible unless later on all the characters say that the tadpole must have chewed on the part of the brain that contains all their previous experience.
I'm enjoying the various backstories the characters have and their different personalities, it's just this part of the equation is leaving me scratch my head.
I have to make Will, Shadowheart, Laez'el, spill the beans about their past but if Gale is an example of what happened they all didi something that brought them back to level 1. The archmage messed up with Mystra ending up killing her and with the need of powerful artifacts to avoid him to explode and erase half of the map with him and unable to use magic as he was used to.
Furthermore the really big and epic enemies can not be killed (like the demon lord in the flying squid), and the mobs in the area are at max level 4.
For our character, well the mindflyers kidnapped pratically any sentient living being they could (ehy, they implated a tadpole in a Gnoll!), so they toke a mr/mrs/miss nobody without any exceptional backstory.
Like I said (and for some reason everyone ignored it), what makes you think that any of them (aside from Gale perhaps) deserves more than level 1?
Who are you refering to? O.o Mine was an answer to really clear and targeted question. The original post wasn't about the characters deserving to be more than level 1 but how lame it was that they start at such low level without any given reason.
What can I say, when I answer a question I usually stay on topic and I not used to make another question to defuse the argument brought by the one maing the question.
Said that, lets focus on you off topic answer:
1) Gale was an archmage able to evoke the personification of magic herself, pretty sure is quite an accomplisment, something no level one can even dream off.
2) Will, he has created a militar force, and his name is known all around, and when he shows up he is frigging powerful compared to other npcs and the playing party (indeed he is the one character that seriously seems nerfed when joins the party);
3) Astarion is an elf turned vampire with two hundred years of experience, one can assume he has trained, unless Cazador wanted him just as a pet so didn't allow the pale elf to train his abilities nor those tied to the fact that he is a vampire, nor those tied to his class, I am pretty sure Astarion wasn't even a rogue before he was kidnapped by the mindfliers (that would easily explain why he is a level 1);
4) Laez'el is a trained warrior in a very competitive race where strenght is highly valued indeed the underlings of her fellow dragon raider are all above level one, so it's just normal to think she is of a higher level;
5) Shadowheart was sent to a very difficult mission by her church, pretty sure they won't give such a delicate quest to a low level adept.