"So, like the rest of us, he might have been inclined, had his rationality deserted him,"

Rationality has nothing to do with it. The culture they are part of don't see the world the way we do; they have no frame of reference to help them understand that a mechanism as complex as a helicopter could exist, let alone be explicable by our science, that is impossibly complex for them to imagine. They could never conceive that folk could build such a thing (were you to sit one of these folk down and explain how it works or bring them back and show them how it's made they might get it as they were intelligent people, but without that explanation they would struggle). The people who built Stonehenge understood the motion of the stars and planets but did they actually understand the true nature of a star or the size and age of the universe? Did they understand the solar wind, magnetic fields, structure of the galaxy, nuclear reactions, gamma rays, x-rays, photons etc?

As humans we struggle with the idea of something being unknowable and seek to explain everything we perceive one way or another; it's why science works hard to avoid bias and a priori assumption. When people think they've seen a ghost they might not be stupid or lying, but might be explaining what they saw in the only terms they know how.