Having dipped my toe in mnemonic techniques, I think part of why we underestimate people of the past, is we have forgotten just how much the human brain is capable of sans external tech.
Yeah, it shocked me the first time I memorized a deck of cards with a memory palace.
Plus, imagine how well trained muscle memories became since methods would have hardly changed from generations before.
One of the Polynesian navigational methods I have heard described, was laying down in the bow of the canoe and going into a meditative trace, thereby being able to feel the ocean swell, and infer the location of distant islands by the diffraction pattern of waves.
https://manoa.hawaii.edu/exploringourfluidearth/media_colorb...