What is the significance of the repetition of the main stages in the evolution of ancestors

What is the significance of the repetition of the main stages in the evolution of ancestors for the development of the embryo?

If we consider the stages of intrauterine development of any animal, then we will notice the “evolution” of this organism. Let’s consider everything on the example of a person. After fertilization, a zygote is formed. After a while, we will see an embryo. He will not look like a born person, but will have a chord, gills, and a tail. All due to the fact that this is how the evolution of man took place. Also, such development is much easier during the prenatal period, since new organs and body parts do not appear immediately, but only at a certain stage, and this reduces the chances of improper development.