While the above melodies certainly have similarties, since the dawn of music millions upon millions of melodies have been written (and among those thousands of famous ones) and thus when one chooses to compose a tonal melody (like most of John William's melodies) it is literally impossible to create something that is completely and totally original. It may be slightly different sure, but there will have been many previous melodies that use similar gestures and figurations like the melody you choose to write - so similar a comparison can be made.
I think John Williams is a good film composer - he is able to create atmospheric and varying moods within his scores, most importantly, and secondly can also spin out a catchy tune if he so pleases. Keep in mind too, that nobody, not even the great composers of the past, is "pure" and free of the influences of previous composers.