The really original ideas remaining to be flashed out and developed are few and far in between:
Most ideas are just different takes on other, older ideas. A new way to see a problem, a solution applied to a different field, a new technology that makes something possible in a different way, … And there’s nothing wrong with that.
The thing that we should all avoid is just make copies that don’t add anything at all. It is fine if it’s a learning exercize, it adds to yourself, but if it becomes something more it should have something that makes it better. Your product should be somewhat different from the competition. That doesn’t mean not to make another weather app because there are already 100s out there, make your own app. The app that you would want to use and couldn’t find. Don’t go and look at the top up and just copy everything they do like a copy machine.
Some examples you can improve on: A particular way it’s designed and used, a specific use case covered, a whole different design that’s actually useful (I don’t like design just for designs sake. Design with no usability is useless.)
Be inspired. Be creative. Be bold.