Are you arguing that history is a science? I think this is a minority view among historians.
And I think you yourself point to at least one of the reasons why history is not a science. History only happens once. We cannot rerun history and change certain conditions to determine causes. (Would there have been a Holocaust without Hitler? For example, is not testable using scientific method)
Historical reasoning is based on deduction on the basis of available sources. Whereas scientific method is inductive and relies on changing conditions and repeated observation.
You argue that new evidence can come along and change the historical perception. That is certainly true and there is some similarity to scientific method and falsifiability here. But it does not make history a science. Because we are not running experiments or establishing general rules from specific examples. (It becomes complicated here because some historians do try to establish general rules such as "what conditions cause a revolution" and so on, but this is stepping outside history into social theory. History is about establishing the particular in a given situation including causes and effects, rather than discovering general rules)
History has a different way of approaching and establishing knowledge from the sciences. That doesn't make it in any sense less "knowledge" than science.
Hence my conclusion that there is knowledge outside science and that history is a good example.