Skateboarding, music, art, writing, code, cooking — all of it counts. Find yours.
A creative medium is simply the material you think in. Painters think in color and composition. Skateboarders think in lines and physics and body mechanics. Programmers think in logic and systems. Writers think in language and rhythm. Chefs think in flavor and texture. What you create with matters less than finding the medium that lets you think most clearly and expressively — the one that feels like a native language rather than a translation.
Most people who claim they 'aren't creative' simply haven't found their medium yet. They've tried the media that were available in school (drawing, writing, music) and found them frustrating or unrewarding, and concluded that creativity isn't for them. But cooking, fabrication, digital design, skateboarding, photography, game design, and dozens of other disciplines are equally creative and require the same fundamental capacity: the ability to make choices in service of an intended effect.
Finding your medium is less about discovery than about experimentation. Try things. Make things badly in different domains. Pay attention to which frustrations feel interesting versus which ones just feel like frustrations. The interesting frustrations — the ones that make you want to try again — are a signal. The medium where you encounter those is worth pursuing seriously.