Why has myth been called the "cradle of philosophy"?

 because back before philosophy ever existedpeople would go to myths when they had unanswered questions.
From the story that told in the myth, people analyze the events that happened to the characters in the myth and took some sort of life lesson regarding a certain value/principles.

Throughout history, myths have make people think and question the world around them. Philosophers have tried to explore myths often and it has led them in many different directions as they explore the world and the people in it. Most of the great philosophical breakthroughs in world history started as myths were explored in depth.