What is a term that refers to book, poem and stories?

Sure, 'fiction'. Fiction includes novels (books), short stories, and fictional poems. It is all about creating imaginary worlds, characters, and events through written language.

The term you might be looking for is 'genre'. It's used to classify stories based on their style, theme, or content.

The term you might be looking for is 'based on real events'. When a fiction story is based on real events, it takes elements from actual occurrences and incorporates them into the fictional narrative. Sometimes, the story might change or embellish certain details for dramatic effect, but the core inspiration comes from reality.

It's often called a 'fiction anthology'.

It could be 'parable'. Parables are similar to fables in that they teach a moral or religious principle through a simple story. They are often used in religious contexts to illustrate important spiritual truths.

This sentence was not very accurate. The essence usually referred to the most important, valuable, and representative part of a book, while the best could refer to a certain article or passage in a book, but it did not necessarily represent the entire book. Because there could be a lot of content in a book, the essence was usually more concentrated and representative, while the best quality might be one of the articles or a paragraph with special value.

Such a book is usually called an anthology. It collects various stories by different authors or centered around different themes.

The Turtledove at the Pass was a poem in the Book of Songs from the Spring and Autumn Period and the Warring States Period. It described the political disputes between the vassal states and the love story between men and women during the Zhou Dynasty. Among them,"Guan Guan Turtledove" described the scene of turtledoves calling out to each other on the river bank, while "turtledoves" referred to birds like turtledoves. According to the Book of Songs, this poem was originally written in the State of Lu during the Spring and Autumn Period. It was a movement about the Zhou royal family. Later, this poem was given a deeper meaning and became a classic poem to express the love between a man and a woman. In the poem, the protagonist was a love story between King Zhao of Chu and his queen, Jiang. The love story between King Zhao and Lady Jiang was called "Guan Guan's Dove" in the Book of Songs and was widely praised by later generations. This poem described the love story between Prince Zhao and the Jiang family, expressing the disputes and wars between the vassal states after the decline of the Zhou royal family, as well as the love entanglements between men and women. It became one of the representatives of love culture in Chinese culture.

I'm not sure exactly. It could vary depending on the type and theme of the big book.

Yeah, it's called a 'dual-story book' or sometimes a 'double-narrative book'.