Why do all the fantasy and sci-fi movies and novels show extra-terrestrials as intelligent beings and more powerful than humans

I have always wondered that why do all the movies and sci-fi novels show ET's as more intelligent and powerful than us. Can't they be just dumb or below us in the intelligence aspect? Apart from this, why should they have nose,ears or eyes. Shouldn't they be completely different and not recognizable. We have always seen in movies that they need eyes to see, ears to hear and they breath or walk. Isn't that completely wrong on some level?