Magic wasn’t mentioned here. We don’t understand the emerging behavior, in the sense that we can’t reason well about it and make good predictions about it (which would allow us to better control and develop it).
This is similar to how understanding chemistry doesn’t imply understanding biology, or understanding how a brain works.
There's no belief or magic required, the word 'reasoning' is used here to refer to an observed capability, not a particular underlying process.
We also don't understand exactly how humans reason, so any claims that humans are capable of reasoning is also mostly an observation about abilities/capabilities.
What surprises us is the behaviors coming out of that process.
But surprise isn't magic, magic shouldn't even be on the list of explanations to consider.