Why was/is King Arthur important

The legend of King Arthur is important because it serves as a touchstone for the first ideas of equality and democracy within England; the democratic ideals that originated in Athens, Greece wouldn't make their way north to England for many more centuries.

King Arthur is a medieval, mythological figure who was the head of the kingdom Camelot and the Knights of the Round Table. It is not known if there was a real Arthur, though it is believed he may have been a Roman-affiliated military leader who successfully staved off a Saxon invasion during the 5th to 6th centuries.