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.