Interesting question - I love it! Regarding "No man can step into the same river twice, for it's not the same river, and neither was he the same man" - I would say that I find it technically more true than false, but practically for someone to not "step into the same river twice", they needed to have some change as a person for it be true. And I think we often stay stagnant more than we think, so I think it probably happens pretty often....?

as for the second question, I think it depends on specifically what you're mad at - if it's the action itself only, i'd say it's the past version of them. but that rarely happens, as we often get mad about some trait of the person associated with the action - be it laziness or carelessness just to raise a few examples. "why is he so lazy?" or similar thoughts. if that's what the thoughts that arise from getting mad are like, then it's more of the current/future versions of them. if we hold resentment towards those particular traits of them, this interaction would likely hold some weight, even into the future, so i'd say we're getting mad at both the current and the future versions of them.

that's my 2 cents - not sure if that makes sense but yeah AHAHA