Short post this time:
The problem with TADC's handling of Jax isn't that it develops and humanizes an irreedemable abuser. It's that it only humanizes the irreedemable abuser.
There is more time spent on exploring Jax's psyche as a character, but hardly any time is given to exploring the victims of that abuse.
In Gangle's case, we only get 1 scene of her ruminating in episode 6, on the deeper effects of the harrassment and bullying that she's subjected to on the daily. But it does very little to actually explore her depths as a person, and moreso is like an extension of the narrative around Jax. Same with the scene in the finale when she cries as Jax is placed in the tent, despite earlier being unable to shed any tears (and if you look at Gangle in the earlier scene, her tragedy mask is missing the standard tear drops. She literally had no tears for Jax)
It's explained away as being "complex human emotions", but the narrative just has no interest in exploring what those feelings actually are, in favor of painting Jax's abstraction purely as a huge loss and a tragedy.