There's pretty much no food in a modern supermarket that will be unhealthy/kill you if you don't cook it. Like, even meat you could pretty much eat raw. But it is easier to digest and healthier when prepared properly and that comes with practice.

Start cooking. Any vegetable can be boiled and any meat or fish can be grilled/fried. You'll figure out with time how to make things tasty, just avoid too much sugar and too much salt. And don't eat anything if it tastes like crap, that will save you from most unhealthy things.