There are precious little fat soluble vitamins in human milk. I doubt seriously that there is enough even for the optimal health of a neonate. I could be wrong.
But there is more fat in human milk than in cow’s milk and almost an order of magnitude more taurine, both helping a neonate absorb more of the little bit of fat soluble nutrients in human milk.
The differences are small vs cow’s milk, which is also not up to par in these fat-soluble nutrients, but the difference makes more and more of a difference over time during the neonate development. How many adult problems had their origins in these problems during neonatal development?