Why would seeing aliens that look radically different from human beings like in the movie Arrival be an upsetting experience and cause an existential crisis for some people?
Warning: Spoilers for the movie Arrival (2016).
Rewatched Arrival with Amy Adams and Jeremy Renner. In it there is a brief scene (@ 57:32) showing riots as a result of the government releasing pictures of the aliens. Why would aliens that look different from humans (two arms, two legs, two eyes, nose, mouth, hands, feet) be so upsetting to so many people?
What is is it about appearances that causes the initial shock that results in outrage for some people? Or was this assumption just for cinematic purposes in this specific movie film?