The author quickly resolves the main plot arc and reason for this fantasy novel series in the first 25% of Book 1. Then nonsensically and convolutedly tries to find "new reasons to continue writing his other world-fantasy novel series. The thing is, humans tend to be the destroyers and supremacists, and that the author makes this other world the opposite does not justify the usual genocide that humans have had of other Beast-kin, Spirit-folk, etc. that are both humanoid and sapient.
So, the author is all over the place in a story that lost it's main plot arc (from finishing it too quickly) and with such an OverPowered Gacha (lottery card skill), well, it's really not moving quick enough because the author lacks the imagination to use light-speed instead of dilly-dallying from Dungeon to Dungeon and from day to day... The serial killer spirit-folk is a little bit over the top, if you ask me...the thing is dungeons limit the level up of an adventurer, if the adventurer is already beyond the scope of the monsters within such dungeon. So if a Spirit-folk is let's say Level 1500, killing level one Orcs is not going to add experience points (XP) towards his leveling up to a higher level. It is tradition to say, that to level up from 1500, that adventurer needs to find adversaries that are higher than his level to gain experience points and help him to level up. Otherwise, that adventurer could kill everybody in this "other world" but if they are not higher level than 1500, they will not add any experience points and thus will not help him level (so it is futile to kill monster hordes that are under your current levels)...
The original idea is great, the story needs editing and some polish to make it even better. The thing is, at the speed the author is going, this is going to be a one-book-show, or maybe a two-to-three-books-at-maximum fantasy novel series...They are in fact so OverPowered, that, the main character, Light, only needs to travel with two of his retinue members to completely overcome whatever problem, adversary or monster horde they might meet on their way...