The explanation we get from skeptics and mainstream science - and who are usually people who have never experienced the shadow people phenomenon - is that it is nothing more than the active human imagination. It's our minds playing tricks on us... our eyes seeing things in a fraction of a second that aren't really there - illusions... real shadows caused by passing auto headlights, or some similar explanation. And without a doubt, these explanations probably can account for some if not many experiences. The human eye and mind are easily fooled. But can they account for all cases?
-The Crafty Witch