@maisonaustyn
Well, he does get exhausted and pass out; which happens a lot in stories where they expend too much energy. And he does try lower level spells in his off-time to find a balance. He very obviously is getting divine backing, but at least there is somewhat of a struggle too not over exert himself. Really, I think the appeal comes from a few spots:
A monster tamer hero is very rare indeed (outside of monster raising games). Plus, the monsters have great personality.
All humans are guest party members. And I think our MC is a possible satire of stoic/emotionless protagonists in so much fiction
He flies under the radar despite being so strong; doesn’t get mixed up in politics, and keeps moving, making it somewhat fresh
Doesn’t excel or is offensively dull. Just kind of a nice read with drama and comedy balanced.
Love the slimes and the fact that he divides his power among his comrades. Too many of these either have a MC who outclasses everyone; or servants that are more powerful or close to the protagonist in terms of strength. This gives the slimes neat new powers too; like storage and photography.