Underrated factor: in this world, humans are naturally selected to be happy and optimistic, regardless of whether it's the most accurate assessment of their circumstances.
Tangentially related, this also marks the point at which proficiency with the conventional tools of modern society (Dust, Aura, Semblance) is decisively shown to be insufficient to face the villainous threat. Not that Pyrrha is the most proficient conventional fighter in the world, but that is her position in the narrative. Mythic, primeval forces are in motion, and it will take forces of a similar order to beat them back.