Canned tuna and salmon are already fully cooked. Canned beef stew, canned spaghetti, canned soups. All of these make a good base for a meal. If you add grated cheese, chopped cooked meat and your own vegetables they will be healthier for you. Canned pork and beans, canned baked beans, canned chill hot beans.
Beans are high in protein and inexpensive.
Canned beans are faster to make than dried beans. Try heating these up and pouring over a baked potato. Top with cheese. You might also try mashing them with a fork. You can put this bean spread on crackers or in a sandwich or rolled in a tortilla.