A vessel that size could serve only one purpose, i.e. escape from a dying world of some sort. It would have been meant to carry EVERYBODY, and not just one or two of each kind or anything like that.
Well those photos are quite interesting. I wonder if that is where we come from? In any event, its not much wonder that China and other nations want to go to the moon.
That formation revealed by those photos would make a very interesting exploration.
I wonder what the NASA commentary about those photos would be.
No way to tell what it is definitively without walking on it.
Fred Nerks is pretty saavy about this kind of thing and so far , she treats it as a bit of a flummox.