Those two sentences in Zhao Yi's On Poetry express the author's belief that poetry needs the times and innovation.

Every generation produces talents, which means that there will be talented poets in every generation, and each generation can only be coquettish for hundreds of years. This sentence means that poetry should have the characteristics of the times. Every generation has its own literature and every generation has its own poet.

The poems of Li Bai and Du Fu have been read by thousands of people, and it is nothing new to read them now. These two sentences are about the innovation of poetry. The poems of Li Bai and Du Fu have been told by thousands of people, and it is nothing new for everyone to imitate them. Therefore, innovation is the key to poetry.