Arcane Schools got a total rework in the remaster in part because Paiso abandoned the long-standing DnD schools of magic. With wizards now free from the binds of those 8 schools, Paizo is now free to build schools around more unique concepts like civil engineering and magical body modification.
The schools in the Player Core are assembled from options in the PF2 Core Rulebook, creating something new and novel and out of existing parts.
