and so the plot moves/restarts before anyone other than the MC can really develop as a character,

The series does something I don’t see often by creating character attachment to side characters through the MC instead of the side characters themself. I think Frieren was a clear inspiration for this series. Although Frieren does it a lot better. I think that’s because Frieren is a loveable dork and seeing her miss a passed-away character makes the reader feel it as well, while the MC in this series is rather bland and most of the time the same gimmick does not hit for him. But since I haven’t read any other LN that works in that way I find it refreshing enough to keep reading and when the gimmick hits, it hits good.