Tom Nook is an honest contractor. He will build you a house and let you pay for it on the honor system with no deadline.
Isabelle is the one to watch...
She finds a patsy off the train to gaslight into being the mayor. A puppet who's only role is showing up for sign ceremonies.
Presumably there was another mayor, one that disappears and is never heard from again.
Old Mayor, Tortimer knows. He's in exile, hiding on an island where she can't get to him.
Her puppy dog eyes have got you under her spell.