George Wilson has a functional purpose in The Great Gatsby that is both thematic and moral.
Wilson is the only truly passive character in the novel. He does not hurt anyone. He doesn’t steal. He is honest, though perhaps a bit daft.
His passivity is his most prominent and important trait because, when tragedy befalls him, it is not through Wilson’s doing. The death of Wilson’s wife Myrtle is tragic for many of the characters in the novel. It leads to the death of Gatsby and determines the future of Tom and Daisy and even Nick and Jordan.
However, these characters knew what they were doing. They were engaged in deceit. We can argue that they “had it coming”, whereas Wilson was innocent.
The fact that an innocent person can be affected by the corruption and greed of others means that we cannot read The Great Gatsby as a book about “getting what you deserve” or as depicting a world where moral actions receive direct, correlative rewards or punishment.
Wilson shows us that everyone is part of the same world, one where you don’t get what you deserve, necessarily.