Some people can sense when people are not what they seem to be

 I am one of these people. I can't always tell you what they might be but I can tell you that they likely aren't human beings.

However, Beings from other planets often "appear to be" Rocks, trees, deer, people or literally almost anything including a car or truck or plane. This is quite common not only here on earth but throughout the Galaxy and beyond.

I think understanding this one is more likely to survive their lives here on earth.

It's simply often people or things are not what they appear to be.

Even here on earth during World war II they were trying to make ships invisible in 1942 in Philadelphia Harbor and wound up not only turning a ship invisible but also traveling through time which appears to be a similar technology. The problem is that many people died when the ship and they became one thing during this experiment.

However, this is basically how Earthlings discovered Time travel right here on earth from trying to make the U.S.S. Eldridge turn invisible.

However, Time Travel has Always existed in this Galaxy pretty much from when this galaxy was created so in relation to the Galaxy time Travel has always been here as a real thing. 

For example, if you were someplace with a Lion or a Tiger or a Crocodile wouldn't you want to know they were there and not just appearing to be something else?

Sometimes not knowing something or someone is different than what they appear to be causes deaths of people here on earth. So, knowing when something is not what it appears to be is a survival Skill. 

And without this skill many people  have died from ignorance of the truth of what they were actually dealing with in that moment. 

However, since many people cannot deal with this truth they are vulnerable just like if a Mountain Lion snuck up behind them while they were jogging or riding a bicycle here in Calfornia and grabbed them by the back of the neck with it's jaws (like sometimes happens to especially smaller women jogging or riding bicycles on Fire Roads bordering somewhat wild lands where Mountain Lions roam.

For example, I'm sort of a backwoodsman in abilities and senses like my father and grandfather. So, if a Mountain lion is stalking me I sense it in the back of my neck and my hair stands up so I know I'm being stalked by something or someone. Having this sense has saved countless people's lives for thousands and thousands of years already.

It's why some people feel safe in the wilds like I do and others don't because they might not have developed these kinds of senses because they just haven't spent enough time in the wilds to have developed senses like this.

So, I would say people in the western half of the United States are much more likely to have developed senses of when they are being stalked simply because it's a lot wilder from the Mississippi River Westward generally speaking, whereas it's a lot more citified East of the Mississippi River almost always which might prevent developing your wilder senses for ongoing survival in the wilderness.