Well, it has to do with the bioavailability, and I don’t have good information for that because the data I have is for babies, not adults. Cow’s milk and human milk have about the same amount of iron for example, but a baby can use 49% of the iron in human milk yet only 10% in cow’s milk. No idea if that’s still true for adults.
The one major strike against human milk is the cholesterol content. Babies and toddlers need cholesterol for brain development, but adults do not need it and in fact need to watch how much they ingest. Human milk has loads of it and cow’s milk doesn’t. So for a baby, human milk is better, but cholesterol may make it worse so for adults. I don’t know how to balance all these things out for the adult human.