Just make sure you aren’t confusing creativity with artistic ability – I have very little artistic ability (drawing, painting, basically generating anything from scratch), but can do a lot with adapting other people’s art. If you like a project, use it as an inspiration point! A lot of amazing stuff is from people iterating on other people’s ideas.
If I were to do a similar piece, I’d almost certainly find existing files to adapt with a shuttle and alien instead of trying to make my own even though they are pretty simple shapes. Basically, don’t feel limited by lack of ability to generate an entire design – the internet is full of options to help you out.