The existence of extraterrestrial beings is a huge mystery that triggers the curiosity of every human being. Some believe but some are also have an opposite belief.
I am one of the non-believers of this specie. Going back in the ancient times where philosophers are still studying about this topic. Philosophers believe that the ancient leaders are having a connection with these beings due to discoveries of artifacts such as carvings and statues that represents some kind of alien activities in these said ancient times. But the question is: Due to advantage of technology these days, if the aliens exists in the ancient times, artifacts that proves that aliens really exist are now discovered or unearthed. Aliens are also called techno-sapiens in the Charles Darwin's theory "The Origin of Man" which is about the evolution of man (which I also doesn't believe).
Somehow your right, but You can't change the fact that the ancient people had no Knowledge nor such technologies to build such Incredible Structures such as the Great Pyramid of Giza Etc. These things would be impossible to be build by the ancient people, which I believe that extraterrestrial beings helped the Humans to build these and to shape our History, or maybe they have more plans in future for the Humans. The question there is, How did The ancient People build those Incredible structure without the help of extraterrestrial beings, and not to mention they also lack of tools or something to be used to build such things.
The human beings built these structures by effort and strength. Humans are the most special creatures on Earth. Meaning we are the most intelligent in terms of development or etc. That's why, even humans on the ancient times are idealistic that's why they can afford to build such structures that humans today think that it is impossible. For example, the Great Wall of China. Chinese citizens made it to protect their kingdom from any assault or attempt of colonization. The Great Wall of China was built spending an enormous amount of time. And until today, we can apply that if we think that machines today used to make products were made by humans. Others just think that ancient people made it with the help of these said extraterrestrial beings. But according to my understanding, time and effort are spent to make those said structures. If the ancient people idealized about the machines today, maybe ALL of us believe that they did it without the help of extraterrestrial beings.
The Universe is like a big vast stretching balloon which is expanding through out the years. How sure you are that these extraterrestrial beings don't exist? And if Charles Darwin's theory is true, someday we will evolved into some kind of an Alien alike being like 'The Grey' which believed by a lot of scientist. Many Astronaut theorist had examine things in terms of these extraterrestrial beings, and they believe that extraterrestrials had connections with Earth not just today, but a thousands years ago. And maybe many people who gained such knowledge had connections with extraterrestrials because there are very explicit. There is no further proof or evidence that is true but, our Universe is quite big, we can't change the fact the we are not the only living specie in this vast stretching cosmos.
That's just a piece of cake. if they really exist in this universe, they should let us know who or what they really are. Not saying that they show up to reveal the world that aliens really exist. But by just giving us enough proof and evidences where every human in the world will believe of their existence. And if they ever exist, they should not be afraid of coming on our planet because they know that they are more advanced in terms of intelligence and technological advancements.