Orphan servant raising arc incoming. My memory of spoilers is fuzzy, but...
Maine actually has a ton of mana. With nowhere to put it, it becomes the Devouring, and eats at her body, making her frail. However, when the church learns of her huge MP pool, they try to take her from her family. For the first time, Maine uses her mana... or actually, maybe the third time. High amounts of mana thrown at others forces a spell of compulsion, so that people with lesser mana must obey.
That’s how Maine got the boys to help her make new clay after they ruined her first tablet, and how she got her dad to take her to the gate or something. To the fat guy, she practically demands he stop breathing, after he threatens her peasant parents, since she’d rather die with her family than be owned by a noble, or clearly, used as a disposable orphan servant MP battery.
Supposedly this huge MP pool leads her to higher plateaus.
Edit: things people can do with mana:
Build buildings
Make barriers around the settlement/country
Weather control
Help crops grow
Iirc. That’s why people with high mana are so important.