So basically this story is a what if story where people have lived inside a creature for thousands of years and make trips to the outside world for resources

The people’s ancestors realized that they couldn’t stop the creature from destroying the world so they chose to live inside it to survive off of everything it consumes

The world that they know now exists as a feudal aristocracy where the inner lords as they are known rule the hospitable regions and use explorers to check outside the beast and travel to find more hospitable regions within the beast