If reincarnation were possible, does it work like a roulette wheel?

No roulette wheel. The purpose of reincarnation is to experience and learn, and this can be accomplished only through exercising your individual free will. You can't control what others do to you, but you can control your reactions to others as well as your directions in life, the choices and decisions you make. There are no quasi-evil deities punishing you for wrongs you've done, and humans don't come back as "lower" animals or bugs or plants. You have control of your destiny through your free will. You learn through the natural consequences of choices you've made. And you design many of the obstacles you face in life - like some people climb mountains, swim rivers, run races - you put yourself to the test, or if you choose you coast along your lifetimes in a sort of semi-comatose unawareness of who you really are - it's up to you.