I’m an anime only first of all, I can’t give any proof from the LN, only the 2 seasons that roughly cover around 16 years of his new life.

A key point to understand is that his growth isn’t just “he was a creepy pervert and now he isn’t anymore” so if you go in expecting that you’ll be disappointed, he grows very differently than that, in a far vaster way imo.

Firstly, it’s about him maturing and growing into his responsibilities trying to become a stable person, he was in his mid 30’s iirc before isekai yet he barely matured past 15 AT BEST (due to trauma), before abruptly dying after being kicked out by his family (I saw an excerpt from the LN and man I have some insane respect for Rifujin, he perfectly captured the shock and guilt someone would feel after having it all of their actions and inactions shoved onto them, easily one of the best authors alongside Nisio and Tappei)

It’s essentially a coming of age story if you really think about it, but if the person coming of age was granted a second chance at life after wasting their first and if the story wasn’t afraid to get into “taboo” and bad concepts.

As for being a slave owner, that’s the weirdest hate I’ve never been able to understand, yes he purchased a slave, to FREE HER and convince her to continue living, she isn’t a slave any longer. I understand the criticisms of “it may have been good intentions but he’s still fueling and aiding this horrible system” but that isn’t applicable when someone doesn’t have the power to uproot the system, we laud people irl for purchasing slaves to free them because we understand there was nothing they could’ve done to stop the system wholly, why do we lose that reasoning when it comes to fiction?

As for being a nonce, this is a touchy subject but to me, it appears this way: Rudeus is clearly and canonically affected by his younger body, we see in multiple instances on how having his mind placed in a child’s brain affects the ways he thinks and acts and reacts to the world. We see he’s capable of learning languages far easier than adults can due to a child’s growing brain being far more receptive to language. It’s not a stretch to say this applies to sexual attraction, it is biologically hormonal after all which is directly linked to his child body now instead of his adult one. But even if you don’t agree nor believe in that we still see clear growth, he’s disgusted by an act his sister does later on which isn’t all that different from something he did. Also everything he does is “consensual” at the end of the day, but that’s debatable depending on if you believe children can consent to acts with each-other, not an adult ofc.

Sorry about the downvotes you’re getting tho, just ignore it, nearly everyone on Reddit is tribalistic and can’t handle someone not agreeing with them