Axies the Collector, also said that he had seen other Giant Spren, like that one. I think the people called it the guardian, but the whole thing did not make sense. It would rise every morning, and put its legs on those pillars, implying that it had always done it. But the pillars could not always have been there, so its confusing.
Also what is the effect of bumping into say a water spren? is it wet, or is it more like a ghost?