Disclaimer: I'm not expressing this as truth; I'm expressing it as purely my own opinion, but it seems that you are looking for opinions, so here goes . . .
I believe that there are two levels to every person: the physical, logical, conscious level that we experience from and within ourselves and everyone around us, and the spiritual level--another level of consciousness (or whatever one wants to call it) that all people are capable of reaching at one point with dedicated focus on it (I also believe in reincarnation so one has a lot of time to find the ability to tap into this spiritual level.) Most have not reached this level, when the mind has absolute control over the body etc., so when we witness someone who has, we deem them (depending on time period/culture) demons, witches, saviors, masters, gods, etc. O'Sensei might have had the ability to tap into his spiritual level (to some extent), and thus perform some great feats that we may believe impossible or unbelievable.
I could have just uncovered the secret meaning of life! Or what I just said could be a bunch of horse crap (most likely the latter
) Either way, I apologize immensely for making you sit through and read this.