Let's first take the anomalous Bigfoot phenomena.... I want you to seriously consider this..... what would be scarier than encountering an unknown man/apelike creature in the woods at night that is HUGE (usually) in comparison to your physical size and that you'd probably have NO chance against? Your life being at risk. (And most could move but don't.)
Now consider that the `alien abduction' phenomena also involves an unknown `creature' that in this instance `came from the sky'.... is imaginably HUGE mentally compared to us (measly humans) ..... and that we therefore are POWERLESS to defend our body against. Our very life being at stake. (And most can't move but would.)
Now consider that bigfoots and UFOs in the same locations HAVE been reported. (one phenomena turning into the other)
Now consider the idea that HAUNTINGS, representative of the unknown human spirits, are considered scary when actualizing or being feared while alone. (Chased by the all powerful DEAD... installing fear.)
Now, all that said, as a human... these do seem to be things to be afraid of. The unknown is indeed..... scary. A potential fear attracter .... and unknowns, some unknowns, simply are 'targeted for an answer' from certain humans. Which in certain conditions ... may trigger actualization.
Finally... I also think that it is certainly possible that the 'Insect aliens' and the 'Reptilian aliens' may be a reflection of those same inner fears we still retain in our DNA for eons as we became mammals and then humans. Are those types of memories some of the earliest fear memories we might have access to experiencing as humans? As conscious spaces?
Please note that I haven't said anything yet about the REALNESS of these actualization's ..... for I believe that is found on a very slippery slope... something that I laid out in my 9 page read of a lifetime be you so inclined.