The thing is, that ewok battle is the summation and climax of the entire saga... and the fact that the ewoks won is the point of the entire theme of the saga: That technology has all the obvious advantages, but when it comes right down to it, the drive, determination, and spirit of living, breathing people will overcome those cold advantages.
That was one of the original concepts (except the ewoks were wookiees) when Star Wars was still on the drawing board. I know they technically aren't human, but the theme is about the power of the "human spirit."
Now, from a more technical standpoint, the ewok victory completely fits. Typically, people fighting for their homes and for their very freedom will have a spirit that is unmatched by any technilogical power... Although, to be fair, I probably wouldn't feel too comfortable saying that to someone from Alderaan.