They Might Be Giants – No One Knows My Plan lyrics

I think this song is written from the viewpoint of God.
In the stanza "In my prison cell..." they are expressing His entrapment by religion; He laments how the religious followers continue to sell Him (and themselves) short by likening them to the cave prisoners in Plato's Allegory of the Cave, expressed in his work 'The Republic':
Plato imagines a group of people who have lived chained in a cave all of their lives, facing a blank wall. The people watch shadows projected on the wall by things passing in front of a fire behind them, and begin to ascribe meanings to these shadows. According to Plato, the shadows are as close as the prisoners ever get to seeing reality. He then explains how the philosopher is like a prisoner who is freed from the cave and comes to understand that the shadows on the wall are not indicative of reality at all, as he can perceive the true form of reality rather than the mere shadows seen by the prisoners.
The viewpoint is amplified by repetition; time passes as God continues His making and creating, again stating the point that no one really 'gets it'.
Another sub-plot in this song is that the listener is almost made to feel sorry for the creator, since all he has to talk to are the iron bars of the prison that his followers put him in with their shortsightedness.