It's a bit of a "the king is dead; long live the King!" thing. There will always be an Ozymandias.

The poem is itself ironic... it's about Ramses III who rule c. 1000 BC and yet was famous enough that poetry would be inspired by him 3000 years later.

I agree. When I was younger, I only got the obvious message about the transience of material accomplishment. The poem is more multifaceted than that.

One starting place is to think about the layers of interpretation (Ramses -> sculptor -> traveler -> narrator). Everyone concerned is still talking, in different ways, about the memory of Ramses.

As long as we're on the topic, here's one of my favorite expressions of parallels between us and people in the past:

https://plus.google.com/+Cornell/posts/MSaUEUpVB8q

This bench sits behind the library at Cornell University.

Lacking belief in an afterlife, many early civilizations instead strove to achieve immortality in "kleos": the fame that does not decay.