How do the interpretations in the poem build the theme?

Here we have a speaker learning from a traveler about a giant, ruined statue that lay broken and eroded in the desert. The title of the poem informs the reader that the subject is the 13th-century B.C. Egyptian King Ramses II, whom the Greeks called “Ozymandias.” The lesson is important in Europe: France’s hegemony has ended, and England’s will end sooner or later. Everything about the king’s “exploits” is now gone, and all that remains of the dominating civilization are shattered “stones” alone in the desert. Note the use of alliteration to emphasize the point: “boundless and bare”; “lone and level.”