Brains aren't magical, if the laws of nature allow for them to exist in nature and we see generalized intelligence develop and get selected for repeatedly then that suggests it can be done - it's just a matter of knowing how.
In a certain way, brains are so complicated that (at least for the moment) they seem quite magical to us
As far as humans not being able to ever understand it, I guess that could be true but I wouldn't bet on it.