What effect does the first paragraph of the story "The Night the Bed Fell" have on the reader? What is its purpose?

In James Thurber’s story, the narrator presents an apparent jumble of details that were part of the events on that remarkable night. He claims that the night was “the high-water mark” of his youth, leading the reader to believe that his childhood was not very eventful. He also admits that it will come across as an “incredible tale” while insisting that “it did take place.” The narrator’s assertions that this event might seem like a tall tale create an expectation in the reader that it will be a fantastic story. At the same time, he mentions that some people who have heard it numerous times do not find it very fascinating.
In addition, while the reader is clearly about to read this story, the narrator asserts that it is better appreciated if performed; at this point, he mentions the assorted details: throwing furniture, shaking doors, and—the most intriguing—barking like a dog. By cramming all this information, some of of it not obviously related and including apparently contradictory assertions, the author both establishes the humorous quality of the story (for those not familiar with his body of work) and intrigues them about what kind of tall tale will follow—and where the dog fits in.
https://www.newyorker.com/magazine/1933/07/08/my-life-and-hard-times-i-the-night-the-bed-fell