Are conspiracy theories kind of like the myths used by sailors in the past when they couldn't explain stuff?

Not really. Old stories explained things in the absense of facts. Conspiracy theories are lies when facts are easily available.
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I hadn't thought of it that way, but that's not too far fetched. I've always thought people didn't WANT to believe–the moon landing for ex.–because to do so would make them change or abandon other beliefs–I have noticed over the years (I'm 61) that some people actually take pride in being uneducated–or, at least, appearing uneducated, I assume so as to be acceptable to their social group.
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Michael Crichton has an interesting take on that in "The Lost World"; the techno-myth. It replaces the old mythology with supposedly modern, hi-tech conspiracies. The irony is that the people who believe this stuff are the same ones who believe that the ancient folks were naive!

Things like the belief that in Byzantium, there's a 10th Century drawing that shows the world from space. That Tesla discovered an incredibly efficient source of energy, but his notes are lost. That much more efficient car engines have been developed, but the oil companies are sitting on the patent. That AIDS was developed by the CIA . . .

Ultimately, though, the moon hoax crap is much simpler than those, and most of the folks who "believe it" do so either because they hear something, think it sounds good, and don't check up on it (let's face it, we all do that at the age of 12), or they don't actually believe anything and just like saying things that they think make them sound intelligent.
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I have a theory about conspiracy theories. I think the people who believe them have some emotional need to believe that the world is a particular way, and that need is so deep that, when something dramatic happens that appears to contradict their belief, they invent facts to "prove" that it didn't really happen, or it happened in a way that supports their world view.
Fake moon landing believers are people with an ingrained pathological pessimism. Confronted with the reality of the Apollo missions, probably mankind's greatest single technological team effort, they cannot handle the fact that America really did those things; the only alternative explanation is that they were faked, which fits in nicely with their negative view of the world.
911 theorists ditto, coupled with a paranoid mistrust of government.
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