I think the narrator talk about freedom and world. When he sad "I'd rather be.." he want a feel like a bird. And He is many times sad, "If I.." because he cant choose anyone, so always say "If I..".. Narrator, If he feel like nail, everything show to him like a hammer. And If he feel like hammer, he sees everything like a nail. And he sad "sparrow" actually almost all sparrow eat nails..
Finally I think the narrator want to say, "What will you want to be, you cant free in this world.
I think the narrator talk about freedom and world. When he sad "I'd rather be.." he want a feel like a bird. And He is many times sad, "If I.." because he cant choose anyone, so always say "If I..".. Narrator, If he feel like nail, everything show to him like a hammer. And If he feel like hammer, he sees everything like a nail. And he sad "sparrow" actually almost all sparrow eat nails.. Finally I think the narrator want to say, "What will you want to be, you cant free in this world.