[Kiwami]

I actually think Proto Drive was human, and Chase is Nr. 000 that was based on said human. You know, Roidmudes take identities and more often than not they also inherit their memories and even personalities, like with Volt.

And the thing with the inability to destroy cores comes from the tech, Chaser utilizes Proto Drive-technology so he also can't destroy cores, with Proto Drive it was the case since he was, well, a prototype.

I'm not sure at the moment but wasn’t 000 still sleeping when Steinbelt „died“? Didn’t we see him once in a flashback, sleeping, before Chase was revealed to be 000? I think he was still asleep when Proto Drive was captured and awakened by using the human as a base. And I think we still have something to find out about the human that was Proto Drive, I suspect he either was Steinbelt's or his colleagues son.