Not everything can be safely stored in the garage.
Some things things need to be accessible at all times; other things we see only every 10 years when we move, but want to keep them anyway. That's why it's important to have storage systems that work.
But there are certain things that don't belong here, no matter what. It's a health and safety thing.
The 3 big no-nos:
Rats would just love to nest in your extra duvet. Let them find a B&B farther down the block. It's also usually too damp for storing clothing; as the items will likely mildew.
In theory, a nice cool room would be a great place to keep extra potatoes, carrots, onions, etc. Ants, mice, and rats think so, too.
Because this room is not insulated, the temperature fluctuates too much to make it a good spot to keep the fruits of the vine.