For the Silmarillion Film Project, we set the
K-T Extinction Event at the fall of the Lamps (so well predating elves).
Galadriel is, of course, old enough to have witnessed the first sunrise (and moonrise), though Finwë is too old to have done so, as he died before that happened. As I said...age can be....complicated!
Elrond certainly has older elves with him in Rivendell. He's not the 'oldest' around by any stretch. But...he's not young, nor the youngest. One way to look at it may be generations. Typically, human families don't have more than about 4 generations alive at once. You may have a chance to meet your great-grandparents when you are a young child. But...likely not get to know them in any meaningful way. When your grandparents pass away, your parents are left with the not-so-comfortable feeling of being the 'oldest' generation left alive. Hopefully by then, you are an adult, and the next generation is alive.
Galadriel is a grandmother. Elrond is a father. Elrond's children are adults. The next generation is on its way, with the birth of Arwen's children early in the 4th Age.
Are there generations before Galadriel? Sure. But are any of them still alive at the end of the Third Age in Middle-earth? Not that we know of, except for Círdan, who is definitely of the generation of Galadriel's grandparents, and likely an elf of Cuiviénen.
It is true that Frodo blurting out 'you were there?!' in surprise over the Last Alliance, which was 'only' 3000 years ago may have seemed silly to the elves there.