Ballet is indeed a good way to train your temperament, but it will deform your feet, make your movements boring, and it's very hard. It is not suitable for such a small child to learn.
Learning folk dance is the best!!!! The most important thing for children of this age is the development of rhythm and body coordination. Dancing folk dance can also develop the child's temperament. And exposure to a wide range of dances, but also the most appropriate basic skills training. Enhance the control power on the legs, arms and waist, and correct the body line.
But the child's interest is still the most important, as long as you can insist on learning it, in order to have the greatest help to the child!