I think the 0-level is a good idea (I have my own 0-level rules that I made up knowing this game was coming out. Different! But these are great)
I think the issue is an RP one. Like in CoC how cultists can be regular joes during the day but whip out the hooded robes at night. So the farmer has a secret room on his farm... you've seen Texas Chainsaw Massacre, it's not unheard of!
Then there's the classic: "learning from your first adventure, you push yourself to master the arcane arts..."
Ditto how the elf goes from 0-level to having a patron they've talked to for years AND spells they know. In theory elves have been around so long they can just chat with their patron, but not at 0-level.
Still, it's a narrative issue. The point is that we now have rules for young kids who go on adventures only to grow up to be big knights. One could start off as Pippen and Merry, and then switch over to the Halfling class in an LOTR adventure.
Another example: Wheel of Time. Rand et al start as 0-level mooks, but discover their potential through the first novel.
Art: I really like the Law vs. Chaos picture. Different artist than the other ones, but not to be forgotten.
The other ones, btw, are fantastic, though. I'd like to see a lot more art like this in the books. You'll notice, on the one p25 and 35 (for the Wizard) that the artist has a fantastic grasp of both 2d and 3d styles? It looks like a simple drawing, flat, stylized, but the direction of the lines, especially on the p35 arm, curve those flat lines to give a really active depth. Neat. Add to that the great penmanship in the inking, especially the good use of crosshatching for the shadows. Very impressive.