No they didn't. In castles meat wasn't very fresh at all, and food poisoning was both common and a common cause of death especially in medieval times. Which is why we have so many traditional dishes that are effectively just ways to keep food fresh and especially safe for longer. How many stew recipes did people invent worldwide, for example? Slow cooking will keep food edible for a week if you do it right. And if you really push it, for months (ie. add animal gelatin as a last step and keep cooking for 2 hours after that, at some point it will solidify and you get something that can be considered "instant soup" by extremely flexible interpretation). If you look back 100 years there are books with year-round menus, and bits of that survive. Why? To give you specific dishes when the ingredients are available according to the "agricultural calendar" as it's called in France. Christmas is great. October sucks.

The very oldest book in the bible contains the basic recipe for keeping meat fresh for ~week, and that's what Kosher, Halal, ... are really about.

And yeah, it depends. Roman emperors, for example, would have had fresh meat available whenever. Medieval kings, no way. Renaissance kings ... probably not constant fresh meat, and certainly not constant fresh fish, but a lot better than medieval kings.