I would agree with that hypothesis, save for one thing. We know the world is the reason we're here and not the Malnosso. They are not native to the world either.

[Oh he loves science talk!]

However, the Malnosso intercept us and bring us into the barrier, which could be done with some sort of gravity well generator. People travelling between worlds would logically have to travel at incredible speeds, increasing their mass. Else they'd never breach the barrier between worlds. The world itself clearly provides some means of safe arrival, otherwise we'd simply be mynocks on a viewport...

[Also musing...]