Ecclesiastes is one of the poetical books of the Bible. 

It is wisdom literature.

The author of Ecclesiastes is identified as the preacher, the son of King David. Traditionally he is identified as Solomon, most likely written in his old age.

The book begins by claiming that all of mankind’s efforts appear to be vanity. He takes this skeptical, pessimistic view from his observations of creation. He claims that what seems to be new, is only repetition. He concludes the chapter by admitting that wisdom alone, cannot satisfy, but only leads to a restless, ongoing search for meaning. 

An initial conclusion to reading this book, could leave a person with a sense of hopeless despair, disillusioned at the monotony of life, and asking the question, is life worth living? What is the significance of my existence?

When the LORD is removed from the meaning of life, life becomes meaningless, and restlessness can be expected.

The covenant name of God, the LORD, is not mentioned in this Book.

Solomon refers to the LORD generically as God. 

These are the reasonings of a man who is thinking naturally, and not spiritually. Don’t make the mistake that because Solomon said it, therefore it’s the mind of God and a teaching to follow in life. 

1 Kings 3 & 11 are great chapters to read to capture the background of why Solomon writes what he writes in Ecclesiastes.