The term extraterrestrial is a word that has been used for a very long time and unfortunately misused. Although advanced beings have the capability to live in space and often spend a lot of time there, space is not their home. All beings, regardless of where they are at any given time, have their origin from earth.
Granted, there are some strange looking beings but understanding the origins of these beings is interesting. With the exception of surrogates, all beings began their lives as humans! A surrogate is a being created by advanced beings to perform a specific job. These beings are not robots but beings with evolving consciousness. Even surrogates, will eventually evolve into human beings. All beings follow the same evolutionary path. All in all, we're not talking about different races of beings that evolved in different places in the universe; we're talking about beings that possess different levels of technology.
I'm not saying that beings from other planets have not come to earth to live because they have, but this is the exception and not the rule. Most of the beings we call extraterrestrial are from the earth! From the time primitive man saw strange craft in the sky or even interacted with advanced beings, it has always been the accepted belief that, "from the sky they came" and because this has always been the accepted belief, people have been theorizing how they did it. When scientists finally rationalized how far the stars were from the earth, they also theorized imaginary transport methods such as wormholes. Without the imaginary wormhole, Captain Kirk, even with a craft that could fly 10 times the speed of light, might have lived and died before he saw his first "other than earth" planet! At best, the Star Trek adventure would have only seen one other planet and they would have to have flown at warp 10 to get there the entire way. The only line from that movie would have been Scottie screaming from the engine room-'Captain, she can't take anymore"!
There is no such thing as wormholes! Anyone who wants to visit earth from another planet would have to make a real commitment to be here. Consider that beings wanting to come to earth from another planet would have to put themselves into suspended animation for a very long period of time to get here and do the same, if they wanted to return. For beings that have done this in the past, it was a one way trip and for beings who have come here and returned, they returned to a very different society than the one they left.
The advanced beings we see here on earth from time to time in saucer shaped craft are earthlings. They are beings, whether humanoid or surrogate, that come from another society- an advanced society from our past! It's easier to understand if you look at it from the perspective of our own society as it is today. Today the people of earth stand at the doorstep of advanced technology. In a few more years, science will discover "other dimensional science". We will be able to build advanced craft which move at lightning speed through other dimensions. This technology will allow these beings, because of their quest for immortality, to be able to live and work in other dimensions. However, when this happens, it won't be everyone who will have this technology; only the rich and powerful will have it. This will be a time of great social division. Rich and powerful is one thing but rich and powerful, with almost Godlike technology, is something else altogether. Society will divide into those who do the work for those who have the technology. The path of advanced science follows the same evolutionary path every time we go through it.
No one accepts second class citizen ship forever. Eventually, the bottom of society rises up and attempts to destroy those who have enslaved them. The frightened masters retreat beyond the grasp of their pursuers, using their advanced technology to do it and the new slave victors take the place of those that had enslaved them.
Advanced beings are immortal but they can be killed. They are vulnerable and so when the time comes for the slaves to become the masters, they go deep underground or they live in space. And the slaves that become the new masters eventually form another layer of lesser technology and so forth. The rest of us just continue to live and die and live and die and live and die!
Beings are not divided by race but by technology!
Great question and good luck in your journey-