The most useful point of view to have here on earth is to see the Earth like people do in "Men in Black" because that is how it really is

 So, there are the provincial people who are more primitive in their beliefs about what is going on and then there are more enlightened beings like you and me who understand that "Men in Black" kinds of realities are here all the time.

So, people mostly are sheltered from the truth much like we protect children from seeing war and mayhem as much as possible so they don't all go stark raving mad and not grow up to be adults.

So, protecting the average person from the truth is what happens. Governments have seen what too much contact with Aliens does to most people.

It's sort of like traveling to a Non-Christian Country when you travel the world if you are a midwestern Christian person here in the U.S. Often the changes are too extreme as well as the culture shock is too extreme for people to cope with who have a smaller view of reality.

However, understanding that Time Travel and the alteration of human memories is a given and always has been is a good place to start if you want to be more enlightened about all of this.