In principle, milk can be regarded as healthy on the basis of its ingredients. 100 ml of milk contains 120 mg of calcium, which we need to build and stabilize bones. Milk also contains an enormous amount of essential amino acids, which we as humans definitely need.
There are also several studies that have been carried out on the effect of milk consumption on diseases in old age. Only a positive effect on cardiovascular diseases has been proven so far. The remaining positive effects are only guesses and have not yet been proven.
However, if you now look at the high number of lactose intolerant people, you might think that milk is not necessarily healthy. But this intolerance is due to the fact that we humans need the enzyme lactase to digest milk and split the lactose in the stomach. This enzyme is fully developed in infancy. However, this development decreases more in some people, while others retain this development.
This ability - to split the lactose - is a relatively new genetic development in our digestive tract. But for all those who cannot tolerate lactose: there are also lactose-free dairy products!