Time in the past, present and future is constantly changing

Why?

Because humans and aliens change it for a variety of reasons.

Humans change time in order so the human race doesn't go extinct. This is the primary use government use time travel for.

The only government I have proof (in that I saw it) in 1992 over Mt. Shasta in action is the U.S. which may be in conjunction with alien nations.

I have no evidence (because I didn't witness it) of other nations or companies or individuas around the world simply because I haven't personally witnessed it while living in this time line on earth, (Earth's present 2nd timeline where 5 billion people did not die like on the 1st timeline in 2001.

So, though I can say I saw the U.S. possibly in conjunction with Humans of the far future alter time or more precisely use a ufo to travel time much of what I'm writing now I cannot go beyond that for a variety of reasons.

Is it important to believe Time travel is real or is at least possible?

Yes. Because otherwise you believe history. History of the past, present and future is not constant. It changes all the time. So, small changes are taking place all the time, and sometimes these little changes also make bigger changes in the present and future.

Isn't time policed?

Yes. It is policed by the Galaxy, by the Time Lord of Earth for the last 40,000 years or more, by Governments of earth through the United Nations since it started etc. Also, individual nations in the Security council at least all have some access to time travel as well.

However, the main reason I can talk about all this is I have no physical evidence at all. Unless you want to consider we all have some devices like our computers and cell phones which are evidence of Alien Contact in 1947 where Transistors and computers chips, and kevlar all came from, reverse engineered from pieces of these things in 1947 and after mostly by U.S. corporations at that time. However, now these inventions have spread all over the world and have also miniaturized time travel devices beyond the big clunky things of the 1930s and 1940s.