Every new artist: painter, composer, author ect. takes themes and ideas from other works that they like and are familiar with until they can find their own style and voice. Paolini is no exception. Even Patricia McKillip who some say is one of the best fantasy writers of our time borrowed ideas from LOTR in her Riddle Master trilogy. I think for writing Eragon at 15, Paolini did an excellent job and I'm sure that this is just his first step in becomming a great author.