You technically could make cheese without murdering a cow but you won't find any made that way. Cows only produce milk for their young. To make milk they need to be repeatedly impregnated over and over again. Lifespan of a cow can be 20 years, though they are usually killed after about 5 as their milk output drops. Half of the cows they give birth to will be male and almost all killed as they don't produce milk. Some of the females may be killed too as you'll end up with more cows than you have room for it you keep them all.

As for a human child, drinking human breast milk is considered vegan as long as it was given consensually. If you kidnap someone and tie them up in your basement then it wouldn't be.

A baby human consuming their mother's breast milk is vegan, because the mother is consenting to it. A cow cannot consent to being forcibly, artificially impregnated for the sake of producing milk. They don't consent to having their horns chopped off. Nor do they consent to their children being stolen from them almost immediately after birth to be butchered for veal.

Yes plant-based cheeses are intended to mimic animal cheeses. But that doesn't mean they have to be identical. Guilt puts a tint on the things we experience, and the way we feel can be considered a dimension of flavor. I would imagine a lot of people would argue they don't feel guilty about consuming animals or their secretions, but that's only because they've never experienced any time without that guilt. If you're used to feeling a certain way every day, you start to forget about the feeling all together, even though it's still effecting you in the background.

The idea with plant-based alternatives is to have all of the good properties of their animal-counterparts, and none of the bad. Cheese that's free of the shame and guilt of causing unnecessary harm and suffering to thinking, feeling, sentient beings inherently tastes better.