In my answer, I've tried to think more along the lines of insects than humans. Since we have proven to be dominant and wiped out every other predator species for the most part, I believe this line of thinking is more true to your story, keeping us lower on the food chain. I'm assuming we developed side by side with these monsters always in our world, and they didn't just spring out of the ground one day through a hell-portal. Even without a high tech or magical solution, for us to have developed to a medieval level of culture necessitates us having survived Stone Age, Bronze Age, etc... and have organically developed agriculture and animal husbandry, cities, all that. It also assumes that these creatures have NOT evolved, you mentioned no real intelligence, tool-usage, adaptation, or problem solving, and they have no innate malice towards us, only hunger. So I focused on an evolutionary answer that doesn't involve us stabbing them many times with sharp pointy things, something we excel at (well, at least until #4)
Satiation as a survival strategy. Since livestock exist in this world, they must have been domesticated from a base animal that survived long enough in the wild to be tamed by humans. Your humans simply feed the monsters a portion of their animals on a regular basis until their stomachs are full. your question made them out to be much more obligate carnivores than chaotic evil killing machines. The bonus here is after awhile the monsters may not even view humans as a food source, and start wishing to not bite the hand that feeds, start coming closer to our villages, and become themselves domesticated, a la Wolves! Domestication. Now we have our own loyal, friendly monsters that can defend us (I'm picturing a deathclaw shephard) In any case, many of ancient cultures provided their gods regular sacrifices of animals, meat, food. Even more recently the church was tithed a portion of your produce. Think of it like a tax, except with tangible benefit. Feed the birds, tuppence a day..
Every villager in the fields wears a bright orange and red frock, that is dipped in the crushed up alkaloid of a poisonous plant, lethal when ingested but safe for skin contact. We go about our regular business and lives, after a few generations, natural selection has every monster avoiding eating anything brightly colored like the plague. Eventually we don't even need to poison everyone's clothes (mimicry). This even fits in with the variation of monster, since most every predator has evolved to shun bright color, equating it with poison
Extremophile societies would doubtless spring up, tribes of people living in the cold north or regions like the hot deserts that the monsters avoid or can't survive in. You would see a dominance of island cultures, even the use of easily defensible peninsulas, and the making use of natural formations. Think the Puebla cities, the Jewish fortress of Masada, or Machu Pichu.. At the very minimum most places would not build their castles and strongholds with an eye toward human-on-human warfare or controlling strategic points, but rather on choke points in the sense of where can the walls be tall and thick, but not too wide. Why build a fence on four sides when you can have three sides bounded by ocean and one good wall? And if all else fails, all the good spots are taken, put your back to the oceans or mountainside and let them taste our spears!
Specialization, one of the hallmarks of civilization. Every farmer and potter and craftsman need not be an expert monster hunter, looking over his shoulder with a hoe in one hand and a spear in the other. Instead, certain humans would take up the trade. Guilds would be established, weapons and tactics honed and perfected, and bounties placed on every monster. Like Saint George the dragonslayer, Van Helsing, or the Jager pilots of fiction- they would be heroes, well paid, greatly respected and honored, and deadly. Lone bounty hunters would take down the merely bothersome sheepstealers and creeping chupacabras, a small posse of deputized locals can deal with a few pesky calla-wolves, and great phalanxes of professionals could take on the legendary maneaters. For story purposes, as long as there is balance, you can make it so the humans haven't completely wiped out the threat. Perhaps our worse angels still surface, and we still war with one another, waste resources on folly, and haven't quite banded together as one might hope in a world of monsters? Or perhaps there are areas where they breed, and are so well defended, so deeply hidden, or utterly infested that we can't manage to competely wipe them out? To the point where it isn't worth the risk of lives to do so, or maybe the guilds could, but like the steady paycheck and interesting work instead of total victory, followed by a big parade, and then shortly after, a trip down to the unemployment office...
You'll notice i didn't really cover the problem of the herbivore monsters eating/trampling crops. Somewhat because it didn't seem to be the true direction of your question, but mainly because this is still a problem today, I've had mice eat every seed in my greenhouse and seen a deer jump an 8ft fence. This is something you can't do much about except by the usual methods we use today on small to medium sized nuisance animals - poisons, weapons, traps, and... well, see answer #1 (im thinking komodo dragon barn cats...)