@WillLi Except he
is changing their culture. Profoundly so, and on damn near every level. He is absolutely imposing his standards upon them in myriad ways even if he chooses not to acknowledge that. His every action reshapes them culturally and even physiologically. And he's ultimately doing it first and foremost for his own sense of satisfaction. He was wealthy and bored and discovered a damn superpower, so he started making use of it.
There's a reason why there are still laws today protecting so-called "uncontacted" tribes. You can claim you're "just offering assistance and they can decide their own fate," but you're still interfering with their development and altering the character of their society. Picking and choosing in that way is
awfully hypocritical. It also exposes the underlying insincerity of your motives.
You say you want to help people, but only
these people because they're easily helped and you can just throw money at the problem. As for
those people, the human beings
born to be owned? That's too inconvenient for you, right? So they aren't worth the hassle? What a pitiful double standard that is. You really are just some jackass playing a part-time messiah. Hell, it's possible that your "help" will entrench and reinforce those means of oppression, allowing that poison to rot their civilization for even longer than if you'd never gone to their world in the first place.
(If it isn't clear, I'm not talking to "you." I'm talking to the fictional character named Kazura.)
Honestly, I got a lot more worked up about this while replying than I was originally. I had simply chalked it up to the usual "hey, it's just a silly isekai" naiveté that's so common with these series. But in continuing to think about it, I've decided that yeah, I do think it's fairly gross. Picking and choosing what people are worth putting in the effort for and what people aren't worth it? No thanks.