Chapter 12, page 24. He indeed has enjoyed his school life. Or at least some part of it (his Tea Teacher, those two guys).
Yes but that stands in contrast to his constant complaining and how he acts as if his only mission is to find someone to marry. He could be enjoying his school life a lot more if he chose to not bow down to everyone (because there's really no reason to).
Also probably since he is knighted and actually got promotion from court, it probably will bring more problem (and undue attention) from court if he outright rejected it than if he get demoted or lost the rank altogether.
I agree he shouldn't have rejected it (higher status means less people able to go after him) but that's not tied to the school, with his adventurer reputation and decent social status he can just fuck off to his island. He has practically infinite money/resources with Luxon.
Chapter 13, page 19. Basically he still think he is a mob and considering those two status (would-be saint and a Duke's daughter) he didn't think he get a chance with them beyond friend
In the dungeon chapter (chapter 3, page 6) he notices Olivia's blooming affection and thinks it'd be trouble if it turned into something more, so it feels more as if he's actively avoiding it rather than thinking it to be impossible. The only logical conclusion I can come up with is that their status would make him too many enemies (but with his power and resources it's not an issue).
In addition he appears to strongly dislike the whole noble hierarchy so why does he suddenly respect it so much as to not even consider marrying above his status?
If it's a matriarchal society it would make even more sense for women to marry men beneath their status as otherwise their husband would have more authority than them in the relationship despite women generally having more societal power (as can be seen with the crown prince and Angelica).
Also I think Leon is closer to usual LN protagonist trope than classic shonen protagonist. I mean, a bit edgy, chick magnet, OP as fuck as plot demand.
I think I was just giving him too much credit, was expecting more consistency with his character but his values also shift as the plot demands it.
At the start he just wants as much power as possible so he can take charge of his own destiny, he had a clear goal and appeared to be willing to go far for what he wanted but frequently also made impulsive decisions for emotional gratification.
Though once he managed to obtain the power to fulfill all of his aspirations he still decides to not grab what his desires and chooses to keep playing the role of a cuck to the noble women he complains about all the time. This is completely different from my earlier interpretation of his character.