>>55763155My personal theory is that Ingo is completely unrelated to the whole shit going on with Arceus and Volo; he's a Faller. Like Anabel and Looker, he's just unlucky soul who happened to slip through a gap in reality and wound up in ancient Sinnoh.
You, who were brought to Hisui with Divine purpose, retain all your memory and have a clear understanding of what to do and how you got here (even if you don't understand why you were chosen or for what larger purpose). Ingo however, exactly like Anabel and Looker, woke up in a strange world one day, knowing nothing but his own name and a vague memory of the past that draws him towards his purpose in life.
Maybe i'm misremembering but it seems like Ingo has been in Hisui for a very long time, and the problems with Volo messing with the space-time vortex are a more recent issue. Ingo clearly doesn't know much about his circumstances, so it's not a stretch to assume he saw the space-time hole appear over Mt Coronet one day (and meet a trainer who claims to have come through it) and assume that must have been where he came from too.