The reality is most people aren't spectacularly important. You won't revolutionize the world, become so famous everyone mourns your death, or be one of the few written in our history books. The same goes for me. But behind each great person is an army of "non-important" people. The secretaries, the janitor, the garbage man, the everyday people who allow the world to function and make it easier for greats to rise. You may not be important, but you are damn near invaluable. Everyone from the past, present, and future has or will play a roll in the history of humanity, important or not.
I don't feel important, yet I understand that's the reality of life. I don't want you to feel like your feelings are invalidated, I just wish to show you, or others who read this, another perspective on what is truely important. It's how you want to see yourself that matters. I can't tell you how to think, but I suggest you find something you like to do (gardening, martial arts, drawing, writing, reading, gaming, running, etc.) And do it regardless of how others see you and enjoy the fact that YOU have done something. That's all matters. And if you don't do anything any time soon, you have your whole life to get started on it.
Tldr: nobody matters but that's fine, at least you've done something or will do something eventually.