In fact, in addition to Journey to the West, Lao Jun's position on the Grand Prix in other books is still very high. It can be said that they are definitely the leading figures of Taoism in their positioning of Grand Prix as an old gentleman. Later, the reason why the old gentleman on the throne was placed under the position of the Jade Emperor was that there was time besides the division of characters in The Journey to the West.
According to legend, in the Song Dynasty, Song Zhenzong was obsessed with Taoism, and the role of the Jade Emperor was only created in Song Zhenzong. As we know, all the mythical figures in the history of China were created by people, especially in ancient times when kingship was paramount. There is no doubt about what the emperor said, so he created the role of the Jade Emperor in Song Zhenzong, and people naturally transferred the position of the Jade Emperor to the position of the founder, Taishang Laojun.
One more thing, in ancient China, the emperor's power rule and ideological rule over the country can be said to be very serious, and the old gentleman or the jade emperor on the throne were all status symbols. The reason why the old gentleman on the throne listens to the jade emperor is also to show the unique position of the king.