Fear would be a understandable, and perhaps common, human reaction in any extraterrestrial First Contact scenario. It would be a big concern in a Direct First Contact situation. Here is a breakdown of possible human fears:
Fear of Attack- Hollywood has primed us for this fear with a million movies about marauding aliens attacking Earth. The threat of attack is a legitimate fear, but only in the context of the actual situation.
Fear of Interference- Concerns about aliens interfering in human activities, either behind the scenes or openly, are also legitimate, and need to be addressed.
Fear of Conspiracy- This worry would probably focus on some group of human beings having a secret deal with aliens that would give those humans an advantage. This could be a particular country or some subset of human society.
Fear of Change- We’re already overwhelmed by changes in our society and our technology. Information overload would be an issue.
Fear of Being Left Out- This could be a fear held by a particular group of humans or group of countries. The fear would stem from being left out of decision-making and not receiving the benefits of First Contact. This will be especially true for developing nations.
Fear of Loss of Control- This will be a concern for many humans, but especially for those who are in control of some human institution.
Fear of Religious Change- This stems from the possibility that information provided by extraterrestrials will somehow undermine particular religions, thus throwing faith into disarray.
Fear for the Future- What will humans become After First Contact? Will we become more like aliens? Will the trajectory for human development be changed? And for better or for worse?
Calming fears will be important in a First Contact situation. International and government leaders will need to speak often to address concerns and set up commissions or panels to respond to legitimate fears. Scientists and other experts will need to put developments into context for the rest of humanity and explore legitimate concerns. The news media will have to be careful about responding to rumor and misinformation. Context will also be critical for the media to truly serve the public. Humanity will learn about First Contact developments primarily from the media, so there is a tremendous responsibility there for journalists, and perhaps most importantly, those who lead newsrooms and media companies.
Everything concerning First Contact would need to be out in the open. Transparency would be essential to prevent misunderstandings and diminish fear of conspiracy. There should be open meetings for all developments in the First Contact process. Those meetings should be streamed on the web for everyone to view. Leaders will need to respond to rumors and misinformation immediately.
Every human would need to be included in the process, in some way. That means all nations need representation in decision-making. Leaders would need to listen to public opinion, and even fringe groups, to hear concerns and respond to legitimate concerns. A bunker mentality could be disastrous for leaders.
The rational middle of human society will need to be fully engaged and prepared to speak out, if necessary. Fringe groups will be quite loud. They cannot be allowed to dominate the discussion.
It may take a while for some of these fears to develop. Leaders shouldn’t assume that a calm public in the first few days and weeks After First Contact means that the calm will continue indefinitely. There will be a period where humans and human leaders are stunned and simply processing information. This will not last. Humans will need to respond quickly to put into place a framework for responding to fear.