... after all the help you've been given, and the doubts you have cast on it, I'm not sure what it's going to take to convince you of anything to be frank.
What it will take is evidence. All the hypotheses put forward are great, and you need some hypotheses to start with in order to have something to test, but a hypothesis is not evidence. When confronted with multiple hypotheses (and 'none of the above' is always one of them, so it is always multiple), you can't just pick one and say it's true.
Sometimes we can't have 'absolute proof' of everything we want in this world.
We can never have absolute proof of anything (outside of mathematics). We can, however, have evidence. They are not the same thing.
Occasionally, we have to go by having faith in those who have greater insight, intuition and expertise than we have ourselves.
Faith is the belief in a proposition despite evidence to the contrary. Faith does not help the search for truth, historical, scientific, or otherwise. Science did not start to progress until people lost their faith in Aristotle.
I had planned to say something about the implicit assumption, in the quoted sentence, that a person who asks a question is acknowledging the 'greater insight, intuition and expertise' of those being asked, but the only polite thing I could come up with is that, while asking a question does acknowledge that the asker does not know the answer, it in no way acknowledges a general inferiority to all those who might hear the question.