Not playing as the main character is actually impossible.

If you are controlling the character indirectly (controlling the environment), you are actually still playing as that character. Gravity can't be a main character.

If you're using another character to control the supposedly main character, the controlling character becomes the main character.

If you name your game by the princess that needs to be rescued, she is not the main character. Zelda is not the main character, Link is.