A small difference could change the history of the entire world.
American meteorologist Laurence once proposed: "A small butterfly flapping its wings above a certain place disturbs the air. Over a long period of time, it may cause a storm in a distant place; even a slight change in factors is enough to cause serious consequences that are difficult to predict."
This theory can be applied anywhere...
Just because of one difference - in 1995, Harry Potter misjudged the creatures he was encountering in Little Whinging, and his reaction was too late, which caused many differences from the original story...
The story has been derailed ever since