Movie extraterrestrials are often so uniform. That's a hypocritical rebuke of best. The concepts of all these uniformities lie within us all; every alien movie you're likely to see, with the exception of Steven Spielberg, most focus on hostile alien invasions.
I've long felt that such stories act as fossilizing agents for the sort of xenophobia that arises out of modern-day globalization. It has convinced me that the one thing we can probably count on, should alien species ever show up, is hostilities of fear-struck masses below. Aggression is one of the most common responses to perceived threat.
But is it really that likely that such beings would perceive us as threats?
I wondered how a giant creature might not appear immediately of sinister persuasion to your random individual. I still don't know, but transparency in action helps put people at ease.