I'm looking for an isekai/reincarnation into a novel/game world novel where the MC doesn't actually get involved with the novel/game characters or gives them little attention, because it's quite frustrating to see an MC "accidentally" does something that grabs their attention, or tries to "save" some sort of character only to start getting surrounded by them, I want the MC to focus on their own life instead of trying to change the fate of the characters. Any genres are okay, I'd read pretty much anything.
Ikemen ni Tenseishita kedo, Cheat ha Dekimasenseshita : (hopefully it'll get off hiatus in 2 years when translations catch up) MC he does get involved with them , but he is living his own life without trying to change anyone else's
I think that Altura’s Defiance & Tori Transmigrated might fit. Altura’s Defiance has the MC reincarnate into an early-story villainess character (who dies) of a Cultivation Novel, shortly before they start cultivating. The MC immediately goes "right, I'm NOT going to make the decisions that the previous owner of this body made in that story", and basically immediately changes the setting of the "starter" area to such a degree that it's unrecognisable to the original story. Sure, she saves the story's MC & initial love interest, but the MC, at least, rapidly becomes someone completely different from who they were in the story. The original story's MC hasn't really done all that much in the plot yet, and their original love interest/primary harem member has gone off to join her secretly related power-house family (due to them lacking members). In other words, this fits because the plot IMMEDIATELY goes completely off the rails from what the original plot would have dictated. Tori Transmigrated, meanwhile is fairly close to what you want. The MC reincarnates into the body of a villainess of an Otome Game she never actually played, having only heard about it shortly before she died in our world due to her name, Victoria, matching that of the story's villainess. In her new life, Tori completely ignores the game's plot (because why the hell would she even attempt to follow it), and actively tries to avoid the people related to it. Particularly the Otome Game's MC. Now, they're both going to the same school, and the game's MC seems to want to start problems with Tori, though she's always keeping sufficient distance to have plausible deniability about it. The game's MC has started to lose her near mind-control level of manipulation abilities over the game's targets about 90 chapters in, but it's only just starting to loosen due to numerous major scenes where Tori publically calls out the insanity of the situation and the problems being made for her alone. Meanwhile, she's doing incredible things and impressing basically everyone who actually matters, excusing the game's capture targets, many of which matter more than said capture targets.
https://www.royalroad.com/fiction/26581/rebirth-in-a-magical-world - this is on royal road u can read it there or u can get extensions to pack it in an epub etc. etc. idk how u read. Its a harry potter fanfic but its done great - has the isekai beginning of a "suffering person transmigrates into a novel and it changes their life" kinda thing and MC does not try to get involved with the harry potter characters at all. Avoids them (to avoid changing the timeline) and does his own thing - learns magic that wasn't in the original stories, lots of focus on exploring the HP world etc.
Not the Heroine, Not the Villainess, but a Side Character...or not? - the MC's is a side character who's goal is to live her own life and to seduce the villainess. The capture targets don't become interested in her or anything, though. Fated To Fall: A Transmigrator LitRPG Tale - the academy arc and start of the RPG the MC transmigrated to doesn't even start until 110 chapters in. The MC mostly just spends her time training and trying to get political power on her own. Memoirs of Your Local Small-time Villainess - this is also a transmigration story, but the villainess character whom the MC becomes has a super small role in the original game, so the MC blows past it quickly and does her own thing.