Later on in the song the adult Barnum (Hugh Jackman) recounts the same dreams. Justin Pau explained to Genius
"We wanted to show a couple of things. One, that this flame of a dreamer that is Barnum always has a vision. He always wanted life to be larger and colorful than it was. We wanted to show that's the kind of thing that ran through the character from when he was a kid to being an adult.
But for the story, we thought it would also be interesting and ironic that he expresses this dream as a kid and when we meet Hugh Jackman as an adult now. He still has that same dream and he still hasn't found that thing. He still hasn't built the house, so to speak. He hasn't been good on the promise he makes to himself and Charity. So that dream is kept alive."