Why the elements exist? Why the formation of a solar system? The people that call themselves scientists might observe the Universe and its complexities to make assumptions about it. The ones made in the past where some right, some surprisingly biased by mistake that came, most of them, thanks to a curious psychological tendency to place the observer in a very privileged state. So, something spins, and it must be the entire Universe and not this planet! It was an example but there are so many others.
When some individual says that "science can explain everything", perhaps is obscuring himself into this theoretical concept as newly it means that the human intelligence (or particularly who says it) is capable of this feat. Al thought, is it? Today is not since the number of opened questions are too high, and some do not see the future, accounting with the past, so optimistic.
At the same time, anyone should take notice of how many individuals, and during what periods of time, are trying in this time to decode substantial complexities present in Nature where the number of factors appears in the order of billions. No individual in this planet is capable of even dreaming about creating a living organism using raw elements of the periodic table. This means that an abstract entity called "evolution" surpasses the available intelligence of every individual or group in the human civilization by an enormous distance.