I have a feeling that Jio is actually a root's child or maybe a monster or something, that acquired the human Jio's memories. We now know that he can take on other identities, so maybe he fully synchonized with the original Jio during that fire and now he thinks Jio is his own identity. That would explain why he's so unaware of his own power and how everyone perceives him.
Why do i feel like mc is actually the one misunderstanding that he's human. He survived a fire and somehow became part of a painting. What if he's not actually human but just got the memories of the human known as seo Jio. Or maybe he did turn to a monster a root's child in that fire. Afterall, he doesnt age. So many questions.