Among the competing theories surrounding the ending, many viewers and critics balk at the most prosaic interpretation of there being a pier, sandbar, or stepping stones just beneath the water's surface. When you think about it, though, the possibility would fit right in with the movie's overarching theme regarding our perceptions and appearances versus impartial reality: If there is a simple, mundane explanation, but we conclude that Chance really does have a supernatural ability to walk on water, then we're making the exact same kind of presumptions that the other characters had been making about him throughout the story.
Chance spending his entire life cut off from society by the Old Man seems very cruel. But since Chance may have had some kind of mental disorder, keeping him isolated might have been a brutally pragmatic decision for the time: considering how poorly run many mental hospitals were around the time Chance grew up, it is understandable why the Old Man didn't put much faith in Chance being allowed to wander into society.
Chance was thrown into the streets with no survival skills, job skills, or any means of supporting himself aside from gardening. It is telling he has to ask a random stranger to make him some food. If he hadn't run into Ben or Eve, his chances of survival in the mean streets of D.C. would not have been very good.
