The original movie (Episode 4) is merely the first part of the Morte d' Artur. Luke is the young Arthur. The Light Sabre is Excalibur, and Obi-Wan is Merlyn. Filling in the rest of the blanks is easy: George Lucas did it; so can you.
So obvious that the producers of the dreadful Excalibur went to extraordinary lengths to telegraph the similarities when that stinker hit the screen. If they could get it, anybody could.