>>53292950>it doesn't help that all of the designated self insert characters are kids either. yume artists have to choose between making an OC, using the main MC, or maybe shippingMaking an OC is something some artists do, but it's rare you'll see the art shared around since it's usually so personal and panders specifically to the artist that it tends to not be cared about by the fandom outside of a little circle of friends. There's also this negative association bordering on taboo about shipping OCs with canon characters, normally because its something only done by younger fans who aren't good at creating compelling characters and therefore most OCxCanon content is just low quality. Not to mention how defensive people are of their favorites being shipped with someone they don't like, let alone someone's random "OC donut steel". This leads to a lot of mocking/bullying which makes the older artists a lot more wary about sharing their work publicly, leaving kids to be the only ones bold enough to make that kind of content and actually showcase it. Slowly it's starting to change, but its still pretty rare to see done well.
As for the other options, shipping can be difficult if there's nobody good enough to suit the artist's personal taste to reasonably ship their favorites with. The MC is always an option though, who can just be aged up or kept as is (kinda depends, I've seen both) but I can almost guarantee that half of the time when the MC is their canon age, it may just be art created by someone in their teens who would be closer to that age. I don't know how often Japanese artists actually care that the MCs are of a specific age or if it's just glossed over, but today in the West everyone is too obsessed with the fact that ~children shouldn't be shipped at all~ so it isn't nearly as common. Also when it comes to shipping using the male MCs, it's definitely just a sexual thing while it seems to be more romantic for the female MCs.