One way to do it is to start with a character that is native to the world but new to the social circles and strata of the story. So that the specific contexts of the story are also new to the character.

Maybe start the charachter in a profession that exsists in our world. The farmboy start like in wheel of time. Or the butcher start like in soaring the heavens. After all most pre industrial people wouldnt have traveled far from their place of birth and wouldnt know much about the world at large.