You are just a stupid, carrot-farming bunny, and you will always be a stupid, carrot farming bunny. you will never become something that is better than a stupid, carrot farming bunny. You recently tried to become a police officer, and you failed. Remember that failure the next time that you dream of being something better than a stupid, carrot farming bunny.
you will never be anything more than X= You will never be something that is better than X.
"Your idea is just a dream, and it will never be anything more than a dream"=it will never be anything better than a dream=it will never become real; it will never actually happen.