I agree with everything you've said. Then the limitations, trying to find them, and though maybe they are always undefinable to the exact, seem to me to be things that go right along with historical inquiry.
My thoughts for now is that I do feel we can rank events in their significance. I think we must be able to. It's just a recognition of the events that have caused a larger ripple effect to occur in the world. So, as of now, I think my history professor was wrong in this regard, if she understood what I was asking her.