David - Thank you very much for your offers to help.
I have solved the problem, although I do not understand still, how or why the problem arose. But I want to leave a brief description for anyone else who runs into this issue. If others with more experience would like to hypothesize why the problem arose, I'd love to hear your thoughts, because I am stumped.
When I created a second character in the project, and exported, the second character was rendered normally. So I knew the problem wasn't the camera. It was the Character.
When I copied all of the keyframes from the first character to the second character, the second character disappeared. Aha! There is something in the keyframes.
So I began copying keyframes, one element at a time (e.g. first the right arm, then the left arm) and exported in between each copy. When I copied over the main keyframes (Human), he vanished. So I simply took the time to rebuild those 12 or 13 keyframes by hand and considered the issue done. I have wrestled with this for a couple weeks and don't wish to invest any more time in it.
Believe me when I tell you I checked EVERY possible manner by which you could make a character disappear (alpha). I could not get that first character back into the render.
Thanks everyone for your help. I hope my description can help someone.