Why is Tigger not in Winnie-the-Pooh?

It's an intriguing question, indeed. Given the popularity and endearing nature of the character Tigger, one might wonder why he isn't a part of the original Winnie-the-Pooh stories. Was there a creative decision made to exclude him? Was there a timeline or storytelling element that simply didn't fit Tigger's personality? Or was Tigger a later addition, created by the author after the initial Winnie-the-Pooh stories were already established? These are just a few of the many questions that come to mind when pondering the absence of Tigger from the classic Winnie-the-Pooh tales.