It's always been fun to tease tourist hikers with stories of the Maero when you're in a remote backcountry hut hearing the godawful screams of brushtail possums.
Speculation is that the myth derived from one or more of the "lost tribes" [1], Māori who fled into harsh wildernesses in the face of invaders. Given we've so little knowledge of archaic Māori culture following the extinction of the moa [2], maybe there were "lost tribes" back then that the Maero is based on.
Amusingly, as a redhead under the Southern Hemisphere ozone hole, they have a myth of a white skinned and red haired people [3] who find direct sunlight lethal, which is pretty correct if you look at melanoma rates in NZ Europeans.
[0]: https://en.m.wikipedia.org/wiki/Maero
[1]: http://nzetc.victoria.ac.nz/tm/scholarly/tei-Gov10_09Rail-t1...