If you don’t have access to canning jars and lids but do have a reliable method of killing and butchering game, you can use an ancient method of food preservation that few people have heard of in modern times.
Sausage casings are nothing but well-cleaned intestines. If you like breakfast, you’ve eaten them before. You don’t have to make sausage to use the large intestine for food storage, though. Carefully clean it of all internal residues, cut your meat into chunks small enough to thread into the intestines, weigh each section down with some reasonably heavy rocks, and knot the sections off every foot or less. Put the weighted intestines in a dense wicker basket or something else that will let water flow in but keep fish and animals out. Then, dive into the coolest part of the river, weigh your intestines down under more rocks, and hope they’re still waiting when you come back. This won’t substitute for a refrigerator, but you can preserve your meat for 24 hours before having to cook it. A day of easy meat you don’t need to hunt can make a world of difference.