What is the function of the first section of "the market in the sky" in the whole poem?

It laid the foundation for the whole poem.

1, with the help of the mutual metaphor of stars and street lamps, from the real to the virtual, the virtual and the real are intertwined, creating a poetic and wonderful artistic conception, laying the foundation for the magnificent imagination of the whole poem.

2, the street lamp looks far away, the light is flickering, just like the stars in the sky. The function is to pave the way for extending from the earth to the sky.

It seems that the poet guides the reader to see, which also means that the line of sight extends to the Tianhe River at infinity.