I've thought about this drawing, and I have certain ideas about it. First of all, I believe its done by Link. I never saw any evidence to suggest otherwise. You could say "Groose did it" but considering OoT came out so much time earlier than SS and that Nintendo isn't very good at keeping continuity, I don't believe this was planned to be connected with their eventual prequel. I can accept the possibility that Nintendo remembered the drawing from OoT and decided to roll with it. The drawing is indeed very similar to the concept of the Imprissoned. If there is a connection between the drawing and the Imprissoned, it was made by looking at the drawing and coming up with something.
I never took much thought to the drawing until I heard a youtuber by the name chuggaconroy talk about it. He mentioned that Link probably felt down because he didn't have a fairy like the rest of his kokiri and this drawing was symbolism of how he wanted to feel important. Given how Link is separated from the rest of his village, this is a pretty believable theory. I also believe that it could be foreshadowing. Though Ganon in OoT doesn't necessarily look like the drawing, Link eventually does become a hero and does have to fight monsters. I believe the drawing to be either those... or just a drawing. They're a bunch of kids living in the woods so finding a drawing like this doesn't necessarily have to mean anything. I did drawings like this all the time as a kid.
So I don't believe it's impossible for the drawing to be the Imprissoned, but its highly unlikely. Though the two images are similar, given Nintendo's history with continuity, I'm not convinced.
