Nice reasoning Architect but second half is a lot more interesting. When someone recommends me a movie or a book, I found that stopping in the middle just because it seems uninteresting left me without a bang in the end.
I'll watch the rest of it later but my fundamental point is still
any set of facts can be strung together in many different ways to create the appearance of intelligence where there is none
Example. I've never been to the ocean, so I go for a walk on the beach and leave tracks. The next day I go back and they're gone! Further, there is a beautiful pattern in the sand. This can't happen on it's own, some active agent must have done it. It looks too beautiful to happen overnight by itself, it
has to be intelligence. I go to a beach in the Caribbean and the same thing happens! Who is doing this?
Or another example, beat a drum everytime there is an eclipse of the sun. I 100% guarantee that the sun will come back. How could this be? Beating a drum makes the sun come back? There must be a sun spirit which is appeased by the drum beating.
All a fallacy, and gives rise to religions, mysterious causes (aliens) and conspiracies alike. The fallacy is not seeing that
correlation is not causation.
People across the world using similiar construction techniques thousands of years ago
means nothing. It could be different people solving the same engineering problems as they noted. Or it could be communication, not direct but through intermediaries. We do see this, science and engineering ideas (especially construction and warfare) spread across the globe back then as neighboring tribes adopt them, then pass them on to
their neighbors. Or it could be just paradigm shift. Read Thomas Kuhn on the nature of engineering and scientific development. The same idea occurs to different people at the same time across the globe, who aren't communicating with each other. Again, common ways to solve common problems.
Wild and fantastic causes
do exist in the world, just look at QM and GR, but you never jump to them without direct proof.