When something develops, it grows. And if you develop something, you create it. Your cold might develop into a rare disease, and you might just develop the vaccine to stop its spread.
Develop is a verb that means to build up, grow, or improve gradually over time. A developer is someone who develops land into shopping malls, schools, and skyscrapers. The process can take months, but eventually they will transform a pile of dirt into a building. Many years ago, people would develop photographs by dipping them into various chemicals. As the pictures developed, an image would gradually appear.