What is it with isekais and always setting the world as a place that's stuck in old ways and never able to progress anything until the MC comes. Like really? No progression in food for centuries? You're telling me that there is not a single cook in that entire damned world that doesn't go outside just using salt as a seasoning?!
It's either cooking, or social reforms, or agricultural changes, or etc etc etc, isekai authors always make it seem like people of long ago were just dumbasses who don't know how to progress unless some rando fucking japanese kid ends up isekai'ed into their world and introduces them to these "revolutionary" new ideas.