You can eat oatmeal raw without cooking it.
Oatmeal while most commonly heated up and cooked and eaten warm can also be eaten without cooking it first.
I sometimes will mix some oatmeal in a bowl with some milk and make like a quick cereal with the oatmeal without heating it up.
This makes for a quick easy oatmeal breakfast when I need something to fill my stomach up when I have no time to cook or just want to enjoy a quick bowl of cold oatmeal.
Oatmeal is just oats and they are safe to eat without cooking just like cereal is.
Oatmeal is fed to horses and other animals as oats raw so humans can eat the oats without cooking them first.
Even babies can eat some raw oatmeal as long as you add some milk to it so the baby does not choke on the oatmeal as the milk helps to soften the oatmeal.
I've eaten oatmeal with and without milk raw for several years now and I've never gotten sick from it.
Enjoy your bowl of oatmeal whether heated up or cold.