Hello! I’m not a Distinguished Winner, but I did win last year. In my experience, it takes time. For examples of strong projects, see https://wwdcscholars.com/ (not endorsed by Apple). It showcases many past winners and helps you understand what judges look for.
Don’t expect to win on your first try. It’s competitive, and I needed two failed attempts before a winning submission. I focus on the intersection of my interests, problems I’ve identified, and native Apple technologies. That keeps me motivated by the problem I’m solving.
Remember that the app is only part of the challenge. Don’t underestimate the essay. Make sure your app and essay reflect who you are as a developer. In my experience, judges care more about your motivations and the problem you’re tackling than a perfectly polished solution.
The idea is the most important part, and it often takes the longest. This year, I went through three different ideas before landing on one I’m happy with. Hope this helps, and good luck!