Jim Casy~ Jesus Christ who is the Holy Ghost. This connection relates to what the oversoul is governed on. That God is not seen but is believed in because of the visible things around the world and the impression he leaves on people. Jim Casy symbolizes this because he is not only a martyr but also the impression he left on the people around him.
"See? God, I'm talkin' like Casy. Comes of thinkin' about him so much. Seems like i can see him sometimes."
I/We~ What used to be one person going through hardships or through starvation becomes We. It is learned that you don't have to suffer or stuggle alone. This helps create one. One group of people working together rather then as individuals.