Birdkin and friends may very well represent these aspects in the inherent qualities of us humans and they are really good for that, I think ;-) The magical personality that has to appear like an externality (as a stylistic device) is like a kind of midwife to what is inherent in us. That's why I never object to witches, elves, wizards, magicians, dragons and other legendary figures. However, readers are warned not to take them literally, i.e. to dismiss them as "nonsense". Otherwise they will cut themselves off to these parts and think that the only thing in them is to put as much distance as possible between themselves and the indirect language, i.e. "watertight evidence". We know where that can lead, don't we?