If you mean biologically- the ones without lactose tolerance, sure. The ones with lactose tolerance evolved to do so.
Morally is a different story, although even there, I don't really see a problem with a subsistence farmer living off of cow and goat's milk. Factory dairy farming is another issue.
I didn't go into morality. I despise industrial husbandry. I'm more than fine with non-intensive farmers having and caring for cows and goats, and chickens, etc... It's fairly symbiotic. I specified liquid, because a large majority of adult humans are not well prepared to process milk. Many are completely lactose intolerant, and some of western descent have some degree of lactose intolerance. Many just don't realize it. Many cheeses are very low in lactose, generally the more cured, the less lactose.
Also, milk has certain hormones which can impact human health.
Humans have evolved to be able to survive by being omnivorous, but being able to eat certain things doesn't mean they are good, it just means that we won't starve, getting a chance to later eat better things. It's not the same to survive than to thrive.