Ideas are great - but execution is king. Because execution is where most of your creativity actually makes a difference in how the idea is represented. If you have a good idea and a good execution, it’s very hard for someone to take that away from you. If you have a good idea, but execute it poorly, someone taking that idea and executing it better will leave you in the dust. But without the better execution that wouldn’t work.
Better execution isn’t always fair though - we often start out in life being unable to compete because of lack of experience, financing, and publicity. But it’s basically how the entire entertainment industry works. Everyone just shuffles ideas around, and try to execute it better (or different enough) from the previous time the idea made the rounds.
After finding good ideas, get people hooked on your execution, and they will not be able to get that anywhere else unless someone else comes along and does it even better, but with practice that can also be you.