Canned anything is OK as long as the can and its seal is intact and not swollen. Canned tuna just tastes flat. Canned flounder would taste flatter.

Dry goods ought to be fine forever as long as they stayed dry. Sometimes it can smell off and you cook it and it's fine. Other times, it smells off and you open it up and find out moths have been using it. If you'll starve to death unless you can eat it, go ahead and sift it and eat. Bottom line is that if it's supposed to be dry goods and they stayed dry, it will be safe to eat. It will come down to whether it's past your tolerance for 'yuck' factor.

The things bacteria need to grow to levels high enough to make you sick are 1) time, 2) temperature, 3) food (protein) and 4) moisture. Some bacteria also require air. The only things you should be concerned about are foods with a significant amount of protien that are moist. Doesn't sound like you've got any of those, except for maybe the cat. If people send you catburgers, don't eat them. Cat jerky would probably be OK.