And you want to be convinced, right? No can do.
You don't see the multiple items, I do without question. Eyes, nose, mouth, spiral hair, layers and layers of other artistic figures. And I see at least one figure, "in the raw", in the "Images" Gallery photo of the mound.
Yours is the second comment using the term "undisturbed". I define that word as "no-extensive-bulldozer work", where modern roads, architected objects obliterate the figure.
Roman settlement? That is modernish history. Go back another 2000 years, that is probably the time-frame I am seeing most of. I have seen 1800 AD photographs of Navajo women wearing that hair style.
Stay skeptical, disbelieving, it is more than ok.