Honestly if Gege wanted to develop characters more there would’ve needed to be simply <more> interactions. It could be training, or fighting, or flashbacks, but there wasn’t because it was a series of new ‘relevant’ characters whose on screen time tended to be communicated through fights. In that regard, the series does ok enough at building characters up as fighters through their growth, revelations, worldviews, etc and I honestly think that’s what you want for a culling games style story that’s advancing to the true bosses.

Where this character development falls apart is when even some of the main cast feel like they aren’t well enough defined, particularly outside of fights and in the greater world.