And btw, not every book is 100% original, most books are influenced by the older classic books, others have a degree of uniqueness around them
I'll address your point. While this is true, and we are very much products of our context, Eragon has done a little more than appropriating ideas.
Most books would borrow ideas and bring something new to the table; Eragon does not.
I would ask to find me five original concept ideas from the first two books and I'll tell you where he's ripped it off from.
Similarly, even discarding this, the book itself was poorly written; ioveruse of adverbs ("Sorry," apologized Brom quickly) including wooden and implausible dialouge, his vocab seems to have been helped with the use of a Thesaurus to deliberately try and impress his audience (which are supposedly children anyway)....
I'll give you this review - read it, and get back to me, it does a very good job at explaining just how bad eragon is:
http://swankivy.com/writing/essays/info/inheritance/eragon.html
loved this quote from that review:
"Okay. Attractive, complex map on inside cover. Flowery language, often to the point of ridiculousness (such as "when he would return, he knew not"). Elves are fair, beautiful, long-lived people with another language. Dwarves are short, stocky, bearded people who wear chain mail and use axes. Dragons breathe fire. Creatures called Urgals are fairly uncomfortable with the sun and speak a guttural language, though there are the "elite" forms of these which don't seem to mind the sun and have multiple times the strength and endurance. All swords seem to have names. Hmm, except for the fact that the name "Urgal" is used and people can actually ride the dragons, I think this might just be Middle-Earth. I kept expecting to see a hobbit."