As a practical matter, you cannot, because unless you are raised by wolves, you are inundated with art from the day you are born, no matter what human culture you belong to.
Sure, but we're not really talking about the practical are we? The question of whether or not an AI is actually producing genuine art, in the same way that a Human does, is more a question of philosophy than of realism.
Theres also an important nuance in that even within truly human-made art, many pieces that are produced wouldn't necessarily "count" just on the merit that a human made it and called it art.
Once upon a time when forums like this were more commonly populated on the internet, I was actually a part of a digital art scene that was based around making artistic images to insert into one's signature. This mostly revolved around using stock imagery as a basis and incorporating it as part of a composed piece.
And commonly, most artists (myself included) had zero issue picking up whatever bits of photography we wanted, even if we were going to unethical means to do so. We (mostly) weren't selling these images for profit, and as it was it was early 2000s internet; nobody cared about piracy and ripped versions of CS4/5 Photoshop were plentiful.
But the thing was, you couldn't just take a stock image, crop it to size, and then call it art. Nobody tolerated that sort of nonsense, and doing minimal edits weren't gonna fly either.
And I imagine once the dust settles as far as image AIs go, their products will be seen in the same way. If all you do is generate an image and present it with little to no actual work, you're not making art. If you utilize that image as part of a composed piece, then you are.
I know it'll be tempting to say thats how its already being used, but it really isn't.
That isn't what I said. So, this is a strawman
I mean, you did just say this:
Being able to make art without having seen art before is similarly lost to the sands of time. Such a person no longer exists.
Whether you intended to say it or not, you are implying that only this one person had the opportunity for original thought and all that followed are merely derivative.
And of course, anthropologically speaking this doesn't support your argument in the way you think it does. Isolated communities of humans and proto-humans have reinvented art numerous times throughout history, without ever having been exposed to another culture or example of it.
You can argue that culturally modern art is struggling with originality, but even artists tend to agree with that. People like Banksy do what they do for a reason, after all, and its why we have serious artists making art out of increasingly esoteric materials and subject matter.
But that has nothing to do with the philosophical question of where art originates from and if humans are capable of it even in a vacuum, thus distinguishing them from an AI who we all recognize fundamentally cannot function without the data they were trained on, and in fact can't even function with only its own inputs, which is another distinction humans have.
Edit: And more to the point, if you recognize that at least one human had the capacity to make art when no art yet existed, then you are acknowledging that this is possible for humans to do.