Did I Just Find a Murder Scene?

Last week my sister and I went to Wales. As if that wasn't horrifying enough, I think I might have found a murder scene:

After driving down this super creepy road…

And walking through this eerie forest…

And down this hair-raising hill…

We ended up in a place called Nant Gwrtheyrn (pronounced like this). Which, according to this newspaper article that was in the "visitor centre," used to be a village for the workers in the nearby quarry. In the 50s, when people stopped buying what quarries were selling, everyone moved out and, due to the fact that the town was almost completely inaccessible, the place became a ghost town. Recently however, a Welsh language school has opened and the area has slightly rejuvenated. So it's now a ghost town with a Welsh language school in it that's really really hard to drive to.

We decided to go for a walk along the beach to check out this abandoned building.

Not sure what it is. I suppose something to do with the quarry. Pretty boring, until we went down into the basement and found…

Bones!

FUCK loads of them.

So what the fuck did I find? I suppose I should have taken a picture of my foot next to some of them so you'd have an idea of scale. But TBH I was more interested in getting the fuck out. There's a Dr. Pepper bottle on the floor near the center of the frame. That should give you a good idea of how big the spine on the left is. My sister is a nurse, and she said they looked like human bones to her. But she reads a lot of true crime magazines and is prone to panic, so I'm not trusting her. Can anyone help me out?

Are they human bones? Did I walk into some sort of Silence of the Lambs fat-girl skin factory? Or some kind of "man eating lions of Tsavo" type situation? Should I feel lucky to be alive?

Or are they animal bones? And if so, why are they in the basement of a building? What kind of predator takes its prey into a basement to eat it?