Star Wars: still one of the ultimate adventure films made. The main strengths here are the original, rich setting and, mostly, the naivete and hopefullness of the story. The story is simple because it needs to be universal (or universally grasped). Another factor of relevance are the characters and their humor; Han Solo may be the most important character of the series (not in a “story” sense, but in a “general feeling” sense) because of his playfulness.

Read also:

Star Wars: The Phantom Menace

Star Wars: Attack of the Clones

Star Wars: Revenge of the Sith