I view game design as a form of art and every artist needs to start off copying other people's work in order to build his own style.
And people should start slow, like making a Galaga or Asteroids clone.
Of course even if you're successful in reconstructing a classic game, that still doesn't guarantee you're gonna be good at designing them but that's still valuable experience.
Maybe you find out you're good at coding, or that you like making music, pixel art or whatever.
Maybe you'll even realize you don't really like doing any of that at all so you will invest your time in something different.