I'm not assuming anything, that is your standard of evidence(scientific proof of existence), in comparison with one example of the historical record.
As clearly shown, your standard is completely useless, as to validation, prior to existence.
As a matter of fact, when compared to any group, or all of the examples of the historical record,
it's failure rate is 100%. Thats a bonifide fact.
Now, using that standard of evidence method, what is the probability you will validate anything, prior to known existence?
At this juncture, your other questions, have been rendered somewhat irrelevant.