I believe this song is full of ambiguity. The very first verse of the song,the writer is saying not that he was actually the ruler of the word that could make the seas rise on his command, he is saying that at one point in his life, he was on top. People all over the world loved him and just by coming out on stage, the crowd would stand and cheer. Now, he feels no one knows who he is anymore, he feels alone, and is now a normal working man.
The writer also utilizes both true rhyme and weak rhyme. For example, world/word, alone/own, key/me, stand/sand, ringing/singing, shield/field.
The only example of alliteration is, "It was the wicked and wild wind".
The chorus utilizes allusion by referring to biblical times.
The writer is the protagonist, as the entire song refers to him. I think you can make the argument that the antagonist is the world around him, as well as himself. He seems to portray that while "the walls closed on me", his own ego had something to do with his downfall.
This is definitely a stock situation of a tragedy. The person who "ruled the world" now has "revolutionaries wait for his head on a sliver plate.