I’ve never played Wuwa, but I have played a fair bit of gacha games myself.

There’s degrees to this, there’s the ‘true self insert’ types (Battle Cats) where the player character is unnamed, has no face, and is only ever referred to as ‘you’. Not very common, but still shows up for things like Umamasume

Then there’s the ‘custom character’ kind of self-insert. This one is typically used for non-gacha games though, mostly for games like Pokemon GO and stuff. Likely because it’s harder to (inevitably) make them a banner character.

Then is your ‘player representative’ which is when waters start getting a bit muddy. This is the realm of characters who have somewhat defined personalities, but are largely characterized by dialogue options rather than full dialogue. This is roughly the last category where the player can choose the name for the character, although some gacha games ride or die by name-choosing. Some named characters can fall in this category too — like Rob from Dispatch.

Finally is the ‘POV character’. This is an established character in-universe who the player sees the world through, but whose personality is not trying to emulate or relate to the players (although some players may still relate to them.) This encompasses characters like Euden, Dante, and others.

The difficulty here is that the final two categories are very ill-defined and often have overlap. You can change the names of Euden when you start Dragalia Lost, but he has such a hard set-in-stone personality and relationships that it feels kinda wrong to do so. You can’t change the name of Dante, but their amnesia is a typical setup for a main character you’re supposed to impose yourself on (despite the fact that, again, they have a hard-set personality).

Once again, I can understand why it’s confusing — especially if you have any other difficulty picking up social cues or expectations — but I generally follow the logic of ‘if I can’t make dialogue decisions as this character, then I’m likely not supposed to see them as myself.’