When Journey to the West first came out, the author was anonymous, but there was no signature. Of course, there was a reason. Eight-part essay at that time, various poems and songs, etc. Mainly popular in the Ming Dynasty, prose is also developing constantly. But the novel is not very advanced and easy to be looked down upon, so the author didn't write his own name at all.
In addition, Journey to the West is not a simple fairy tale, it reflects many dark sides of society and satirizes related themes. For example, The Journey to the West's most brutal king alluded to Zhu Yuanzhang, while The Journey to the West's ignorance of the truth was gruesome, and if it was not liked and recognized by the authorities, it might bring disaster.