I assume he wasn't meant to be level 1 to start with, considering he said it was his exceptional prodigious skill with magic that made Mystra attracted to him, though that doesn't actually make him being a level 1 character much less silly.
I noticed with D:OS2 that Larian has a penchant for introducing level 1 characters with level 20 backstories. It was so bad in D:OS2 that I completely lost interest and stopped playing it after about 3-5 hours. So far, Gale and Karlach are the only ones I've seen in BG3 that have super off-putting and severely out of place for the level of character backstories. I haven't uncovered enough of Lae'Zel or Shadowheart's backstory to tell if they're equally as bad. Wyll seems to be a bit in the wrong direction (but I force myself to make the assumption that you aren't supposed to recruit him until at least level 4, and that makes it almost palatable) ...and Astarion can be excused because he was basically a mindless meat puppet for the last 200 years.
This is one of the main reasons why I want to have the ability to just roll with a party of completely custom made characters. I've been role playing since the 3rd grade (I'm 44 now). Having my NPCs not have any story options at all is much better, to me, than having them have stories that are completely out of place for their level. It doesn't break the experience nearly as much for me to have nothing there as it does for me to be wondering how I'm supposed to believe that they accomplished feats that would require a level 20 character to even attempt while they were still basically level 0.
