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.