Ozymandias: Why speak in such a way?

Ozymandias had a very interesting way of explicating a meeting of a vast traveler from from an "antique" or as I see it old land. Percy Shelley seemed to write this poem in third person even though what he said was obviously in third person. He seems to be telling a story from another's point of view or experience. Shelley might as well be the one that experienced the antique land from his starting sentence, but as I kept reading it seemed to reveal more. My theory is that he wanted to be Ozymandias or was very interested in learning about him since he took an experience from him to make as a poem. At first he makes Ozymandias seem like a normal person experiencing the hot desert for the first time, but then he introduces himself as the "King of Kings" just to show how powerful he is and that nothing can keep him down in the lone and level sands so far away. He also goes into say how the traveler felt, like he was without a torso and how his legs felt so stiff he barely had filling in his legs, and how the desert was playing tricks on him and how he was tired of the lies of the desert. Ozymandias talking about how great he is and how he will overcome the obstacles the traveler faced shows the comparison between characters and how Shelley just seems to give favor to Ozymandias over the traveler. Maybe Shelley just wanted his readers to know how much he wanted to be immortal like a King so that he too can overcome almost anything.