5 ideas
Dawkins asks the reader to picture photographs of themselves, their father, grandfather and so on back through about 185 million generations, stacked like books on a shelf. Every photograph looks like the same species as its neighbours, yet the far end of the stack shows a fish. This is why there was no 'first human': species change continuously, so any boundary we draw is a naming convention, not an event.
Dawkins separates three meanings of 'magic'. Supernatural magic is myths and miracles that break natural law, and he argues it does not exist. Stage magic is trickery that only seems to break those laws. Poetic magic is the awe we feel at real phenomena, and he claims science delivers this in greater measure than myth because its explanations are true and still astonishing.
When someone reports a miracle, ask which is less improbable: that a law of nature was actually suspended, or that the witness was mistaken, deceived, hallucinating or lying. Human error and dishonesty are common and well documented, while broken natural laws have never been reliably demonstrated. So the rational default is always to doubt the report, not the law.
They built mock airstrips and drilled with bamboo rifles to summon the cargo back. The cult formed within living memory and grew documented legends that contradicted one another, which shows how quickly myths arise and change, like Chinese whispers.
We know what is real in three ways. We can observe it directly with our senses. We can extend those senses with instruments such as telescopes, microscopes and spectroscopes. Or, for things we cannot observe even with instruments, we can build a model and test the predictions it makes. A claim that cannot be checked by any of these routes, however old or widely held, has no standing as knowledge of reality.