Just a few other thoughts -
When you say "You just have to read and listen to the accounts" what you're really saying is that we're supposed to read, listen, and trust. That's a problem.
You are trusting that the people claiming to have worked in classified programs are telling the truth about who they are, what they did, and what they saw. People can fabricate stories, people can be deluded, people can mistake what they've seen. There are SO many variables here, so I'm not sure why you've placed your faith in people who at best can say "Trust me, I saw something.". That's not good enough and it's not actual evidence. Even videos and photos cannot be trusted anymore.
Basically, there is no way to prove the existence of flesh and blood aliens unless we observe them for ourselves, and even then we should be testing the spirits and questioning everything.
You can't prove what aliens are or are not, but 'testing the spirits' doesn't negate flesh and blood. Read this again:
1 Jn 4:1 Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.
The passage says to test the spirits, and in this case of a flesh and blood person - such as false prophets - to see if they're from God. Similarly, if a person has an encounter with what they think is an alien, they should be testing that spirit no matter what.