These thin, rubber-like threads pull on the skin, which is why the skin is always tight. The reason why babies' skin is especially tight is because there are thin elastic fibers in their skin in various directions without any gaps.
However, as the baby gets older, the elastic fibers gradually lose their elasticity. Finally, they lose their elasticity completely. The skin then sags and wrinkles. Once elastic fibers are lost, they cannot be renewed. Therefore, once you get old and wrinkled, you will never be able to get back to normal again.
By the way, the palms of our hands also have many wrinkles, but these are different from the wrinkles that form when we age. These wrinkles are called kinetic folds, and they are the result of repeatedly grasping and folding the hands over and over again.