In the mid 1940s, post WWII, Langston Hughes was disillusioned with the Harlem Renaissance. Having seen the "New Negro" movement built from nothing to something potentially world-changing then fall back to nothing over the course of a couple of decades, he was capable of speaking to the faults of the people involved. He knew all of these people and was right alongside them for years, so he was more than qualified to condemn the movement in retrospect.
Hughes records his life experiences in memoir form in The Big Sea. He isn't concerned with presenting an accurate representation of how he experienced events so much as reflecting on how he views those experiences when writing the book. From being a young boy desperately believing he could write good poetry to his pursuit of a career as a bohemian writer, Hughes records his journey.
Hughes' main criticism of the Harlem Renaissance is that the artists who were part of the movement had perfectly positioned themselves to accomplish social change for the betterment of their brethren but didn't deliver. He doesn't excuse himself from culpability either. Hughes fully admits his own negligent role, while confessing the sins of his fellow writers as well. They weren't doing anything morally wrong, except that they had been granted positions of influence and chose to use that influence selfishly, to better themselves. Fame and fortune won out over the cause which made them famous in the first place.
