I've always loved this song. I had the old white cassette tape with the ink rubbed off from overuse. When this song came on it was a instant shuffle for the volume knob to turn it all the way up.
*I think songs with words should not have one meaning. I think they should be heard as if they were instrumentals. And they should mean what ever the listener wants them to mean.* With that said...
My interpretation of this song is that the song itself is a melancholy toned symbolic and yet literal reflection of the artist's work and life. The first verse is the writer's explanation of how he feels about his work and life compared to others around him. He observes "Someone and someone" "looking for something to plant in the lawn" and others "turning the soil". When one plants something, they're setting, furnishing, establishing, introducing, depositing, and creating something. He witnesses people giving birth to things around him. Then he reflects on what he's doing and realizes what he is doing is worthless, and a lonely act "Sitting here hoping, this water will boil". He feels his work and life has no purpose, meaning or significance. But yet he is still admired and sought after. "They're bringing me presents and saying hello." I think he is puzzled by the fact that something he views as worthless is so valuable to so many.
The chorus is the writers literal explanation of what he does. "Singin words between the lines of age."
The second verse is a hypothetical question to those who value his pointless, unfruitful work. He's asking if I wasn't famous and a star ('if I was a junkman') but was still doing insignificant work ('selling you cars, washing your windows and shining your stars' though we rely on cars they are a burden; we lose money when we buy them new, they require gas, oil, water, maintenance, insurance, tires, they are a pain in the ass) would you still "bring me presents and say hello" "what would you wonder and how would it seem" how would you feel about me then?
The last line in the second verse is the writer going somewhat crazy but staying on the path he has been on. Even though he feels uninspired by his work he "The King" is still "living in castles a bit at a time" meaning he is merely or hardly living. But yet he laughs and continues his worthless work "The king started laughing and talking in ryhme".
I hope Neil was just having fun with words and my explanation is just bull. If one were to actually feel this way it would be HELL.