This song -i think- means that the first three verses are where he recounts his former glory "Old king is dead, long live the king" when he was going to rule the world, and how he held such power over his enemy. "I used to rule the world/ Roll the dice" And then he tells of his downfall, when he sees that he cannot rule the world, and how he has become the lowest. "Now in the morning/ sweep the streets I used to own/ the walls were closed on me" Sweeping is a nobody job, so He is saying that he is now a nobody.