You have to invent the right thing. Some things you might invent:
A solution to a problem. Nothing novel, just an answer for a question. Eg. any Rails/Django/etc. application.
An application of some existing techonologies in a novel way. Eg. integrating a library to avoid inventing your own solution.
An incrementally better, specific kind of mouse trap. Eg. building on top of existing infrastructure to solve a problem better than any existing solutions.
An entirely new kind of mousetrap. Eg. building wholly new infrastructure because you face a high quality, unique problem that you are imminently required to solve.
Inventing the wrong thing means you’re operating at the wrong level. If you’re too high, you’re spinning your wheels on problems you hope to have. If you’re too low, you’re spinning your wheels on building something that isn’t sufficient to solve your problems. If you’re at the right level, you’re mostly solving problems you actually face and not solving too my coincidental problems.
This doesn’t mean new problems shouldn’t be tackled and new techonologies should not be invented. It applies mostly to reinventing wheels. That is, a project starts with level 1, not level 3 or 4. Apply a technology and improve it before you push the edge. In fact, you must push the limits of an extant technology before level 4 is the right answer. No skipping allowed.
Don’t let imposter syndrome lead you to the wrong technology decision. I’ve tried to build at the wrong level in the past because I felt like I had to fit in with the level of what others working on larger systems were building. Wrong answer.
It’s OK to build a scooter instead of a spaceship if all you need to do is go pick up the mail.