The cave—sealed off until its discovery in 1931—was uniquely able to preserve the human remains, which were mixed randomly with animal bones, broken pottery, and stone tools.
The human bones weren't the whole set, and they'd been defleshed--easily, without heavy scraping. "Some of the bones had light cut marks, suggesting that only residual muscle tissue needed to be removed by the time of defleshing. That meant the remains were likely deposited as much as a year after death." Or maybe they'd been boiled?
But what was the significance of the cave? Robb and his team further hypothesize that due to the similarity in appearance, bones might have been regarded as equivalent to stalactites. Indeed, noticing the connection between water dripping from the cave ceiling and stalactite formation, the Neolithic Italians had placed vessels beneath the falling liquid to collect it; as the substance that created "stone bones," it likely had a spiritual power. It’s thus possible, the team says, that the cleaning process and deposition in the cave was a way for the living to return the bones to their stonelike origins, both in appearance and location, completing a cycle of incarnation.
But if the site was so powerful, why toss the broken pottery and leftover scraps there too? It's possible that broken pottery was special (maybe single-use stuff for a ritual), and maybe the (not described) animal bones were part of some sacrifice, but it still sounds as much like a midden as a burial. Though maybe Haggard knew of something I haven't heard of.