[Rune Son of Bjarne]

Plenty of Elves died in the first age, could it not be some of the major characters from the Sil?

It could be that the elves of Rivendell found statues decorative. . .

Personaly I think they add a bit of atmospere to Rivendell when watching the movies, it gives the impression that it is a place that have excisted for a very long time and maybe that is the reason they where put there by the movie makers.