Could I have an explanation of "Ozymandias" by Percy Byssche Shelley, line by line? To whom does the word "them" in line 8 refer?

Ozymandias by Percy Byssche Shelley relates the tale of the once proud and defiant Ozymandias, king of all he surveyed. The story is told by a narrator who "met a traveler from an antique land." The "antique" land to which he refers suggests that it is an exotic and interesting place of, no doubt, much historical importance. The narrator goes on to tell the "traveler's" story of nothing more than "Two vast and trunkless legs," which he came across in the desert. On closer inspection, the traveler spots something that is partially buried by the sand and realizes that it is an image of a face, " a shattered visage."

The traveler notices the "sneer of cold command" immediately, inferring that this was the face of someone of enormous influence or "command" but also someone with a high opinion of himself but with little regard for his subjects as indicated by "sneer..." and "cold..." The traveler complements the sculptor who "well those passions read," revealing that the sculptor was obviously not fooled by Ozymandias's commanding presence and recognized his arrogance. The traveler is enjoying the irony that what has remained of the apparent, unpleasant character of the man is "stamped on these lifeless things," rather than any indication of his greatness.

"The hand that mocked them," refers to the sculptor's ability to sculpt this image and reveal Ozymandias's weakness and arrogance, which character flaws he describes as "them," and, unknown to Ozymandias, to mock him whereas Ozymandias only thought about his own greatness - which "fed" him. There is also a plaque still visible which sets out to describe Ozymandias, the great leader and "king of kings," in his own words as he calls on other great leaders to, " Look on my works, ye Mighty, and despair!" He thinks that other leaders will despair because he has so much more than they could ever wish for. This is particularly ironic as "Nothing beside remains." There is only "that colossal wreck, boundless and bare," a stark reminder of how Ozymandias's greatness is nothing when compared to the "lone and level sands" as they "stretch far away." Ozymandias's perceived greatness should serve as a warning to anyone, that vanity serves no one and that any personal vision of grandeur is fleeting and inadvisable.