I thought they were only descended from Alyeids, who were actually the ones to introduce magic, build white gold tower and pretty much stand above High Eld achievements. The Alyeids got overthrown by their human slaves too xD
Also, really no one has any business in Tamriel because the continent was only originally inhabited by Argonians and Kahjit, everyone else came from else where
And I don't think that's a compelling reason. Its like saying the Greeks are superior to everyone in the world because of ancient Greek achievements, or the Arab are superior for vast medical advancements, or the Chinese for being grand innovators in ancient times. If you like, Italy is superior for its construction achievements during the days of Rome, or the British, French and Spanish superior for bringing 'culture' to the 'savages'.
Certainly the past can be used for merit, but nobody can claim superiority based on it, especially when all races have achieved great prowess in particular fields. Imagine Nords believing themselves superior beca... Oh, wait... They do.