So, that's called life.
During life you do spend a lot of time wondering what the heck you are doing here after all. Some people say the point is not to find the meaning of life but to make your life meaningful. Others prefer to just enjoy the ride and make the most of it. Your mileage may vary and nobody knows what paths your life will want to take.
But there's one thing that makes life so vivid and that is death.
Without death you would never reach even a partial conclusion of what to do here because you just wouldn't be bothered to and you would be procrastinating instead for your whole life. Death conveniently and equally applies to everyone, and it makes you think about what really matters for you in your life.
The unescapable end of your life may seem like a long way ahead for someone who's 21 years old but when you're older it feels that was just a moment ago when you actually were 21. Years go by quicker than you think, and each year you will be thinking about it more and, most importantly, prioritizing your life accordingly.
Some people see it coming early, and make a better life of theirs after that realization. Some people hit it late, but that's all right too because eventually you will not only merely know but also realize, with all the cells in your body, that you won't be here forever. For real. And why that matters is because you know you can't fool yourself anymore.
And suddenly then some things don't matter anymore and other things really start to matter. You will see for yourself at the time but I'm willing to bet a lot that your career won't be one of your key questions.
Rather, it sounds to me that what you were really worrying about was whether you will "never ever create something that truly changes the world". But that may or may not involve your career: you don't know it yet. Life unfolds in most unexpected ways: if only you go with whatever works for you, you will bump into something that truly changes your world.
And it is then you know what you will do with the rest of your life.