Ceviche is marinated in lime juice. The citric acid has similar effects as heat.

Sushi on the other hand usually contains raw fish indeed, which is why it should only be eaten fresh.

As for cooking beef, there’s certainly a reason why our ancestors invented cooking. It helps with making food more palatable and safer to eat. When heating tissue above roughly 42 degrees centigrade proteins start to denature, which renders many pathogens inactive and harmless.

The gastrointestinal system of modern humans can’t stomach many types of foods raw either because we lack the enzymes to digest them.