My hypothesis.

"level 1 thru 6" of an NPC both has narrative reasons "this person has little power, agency, status" and meta game "we need this wee bastard to stay alive at least til chapter 4"

for example, archer and clay are both ex leaders of the wet boot boys. But archer is a 3 and clay is a 1. yes clay is a one because he needs to be for early embrace, but clay needs a life coach. for his age, abilities, etc he lacks "agency" or power.

the perfect example of this is are veteran couple. one is a 1 and one is a 3. the one is the one with the most crippling PTSD.