This suggests I would be more at home with alien theorists, but they too take a good theory and discredit it with nonsense. Science / atheism however, don't go far enough. It seems as though each hypothesis (and that's all any of them are) excludes the possibility of the others. People adopt a creed according to the programming they have received then put the shutters up, blocking out any thought that may compromise the inflexibility of what they have been told. In essence, people can't think for themselves. There is an inability to reason beyond what they have been taught.
So here I am with my own private 'religion' of one. I can no more prove my theories than you can disprove them, nor do I feel the need. However, my intention is not to tell you what to believe, I just want to put a few more options on the table. You have to open your mind and make a decision you haven't been told to make. In brief this is my train of thought.....
In the past, Earth has been home to intelligent life-forms at least twice before. One was more advanced than us technologically, the other followed a more 'natural' course of life where technology was largely shunned. The earliest inhabitants were what we today would consider the most advanced, simply due to the technology they developed. I personally believe the inhabitants of 'Middle-Earth' to be more advanced, simply because they chose to restrict development of technology.
Now we all know the planet can be a pretty inhospitable place at times, just ask the dinosaurs, and ELE's (extinction level events) have occurred a number of times. This most likely put pay to the inhabitants of Middle Earth with their inability to evacuate the planet, but could some of the earliest hominids from the first phase have escaped? I believe they did, and it is they who are responsible for the events in my 'Agnostic Bible' (available to subscribers of TotallyJP.com).
There is the possibility these Gods / aliens / evacuees who are largely responsible for the way the current batch of hominids have evolved, may not have come from Earth at all. It's probably a little more plausible to many but I just have this gut-feeling. In a similar way I have a nagging thought that could make interstellar travel more plausible. We are constantly looking for methods for propulsion yet if we managed to leave our heliosphere, wouldn't a method of braking be more appropriate.
We are under the impression that we cannot solve the puzzle of human existence because we don't have all the pieces. I believe we do, we just can't see the obvious. Humans today can create life, genetically modify and clone species, and yet we have only explored a fraction of the depths of our oceans. We venture out into space when the answers might be here all the time. There are other possibilities yet I still feel extra-terrestrials / Gods are most likely to have originated here on Earth.
Taking the evacuation hypothesis as true, we then have to look at what happened to those who escaped into space. After an ELE the Earth can take thousands of years to stabilise and become habitable again, so the initial goal would be to find another planet to
Imagine if we as a species were evolving in the sterile environment of a space craft. We would lose characteristics in time. Hair, nose, ears would become obsolete. Eyebrows and lashes would go as would the iris. The skin would become pale (or grey) due to a lack of exposure to solar rays, skeletal features would change, etc., etc. It is not difficult to see how a typical grey alien may have evolved.
This is just one side of the coin, there were pitfalls to evolving in such a sterile environment. An intolerance to harmful solar rays and all manner of bacteria would develop, in much the same way lost tribes are susceptible to our diseases. Grey aliens are probably allergic to us in the same way lost tribes are. I could take this much further but personal beliefs are exactly that, personal. For an insight into how I formulated this opinion it is necessary to read my other work and Redefining Atlantis is a good place to start.
To conclude, when one theory can explain ALL the supposed mysteries, it would be wise to at least give it a little consideration. Open your eyes, unblock your ears, slap yourself in the face and engage your brain.