I agree with @Jonathan-Malski about the contrast on the left side of the image drawing attention first, but I absolutely love the gentle contrast of the ghost's top half with the soft lilac/pink/blue background. If anything, the contrast at the ghost's bottom half makes the figure feel too solid to me.
The ghost does seem static when placed in the center. I wonder if the ghost were placed further to the right, so that the viewer gets that great payout of seeing the ghost after one's eyes travel over the market.
It may run contrary to the story you are telling, but I also wonder if the ghost could be more actively turned towards the viewer. Silhouettes don't draw the viewer in as much as a turned head (which may be what you're going for, as it makes the ghost seem more isolated.).
Placing the ghost figure on the right, looking and facing out of the picture plane, might make the composition feel unbalanced. But if the figure is on the left side, it may seem the ghost is interacting with the market in an un-ghostly manner.
This is such a lovely piece and makes me think about the characters. Engaging.