The core books include only one use of the word disfigure, that use is in reference to a magic item animating corpses that have injuries or disfigurements & doesn't really track to the sort of usage you are using. I don't even think there is an "x-y represents typical" in anything with more weight than the simple coincidence of 10x6 for commoner & certainly couldn't find any.I mean, it's your game, you can do whatever you want with it.
For me, the costs and overall number of points you gave don't make any sense at all in the general context of D&D settings and npcs: most humanoids will have an average score of 9-11 in all stats. Of course there can be the horribly disfigured, the exceptionally weak and the incredibly stupid, but those are serious exceptions. With this system, you're pushing character creation to be absolutely mediocre, otherwise most characters will be savant in one stat and absolutely horrible in everything else. Not fun, IMO.
For the same reason I also never liked the swinginess of dice rolling stats and the crazy 3-18 spread of stats. It can be interesting to play a character with a particular weakness, but it'd rather do it in a different way (addictions, other kinds of flaws etc) than a dump stat.
Stats play a modest part in the overall LU and o5e maths: proeficiency (or lack thereof) immediately imparts a +2 difference (and it gets wider with higher levels), and expertise dice can boost the outcomes even more. The distinction between a specialist and a generalist comes from where you put your proeficiencies and expertise, not from your stats.