This is too simplified. What is the state of a person? It's an object of infinite information, the question what aspect you focus on is very non-trivial.
You don't have to disbelieve anyone who says a certain aspect of a persons life typically has little influence on their later life.
Another issue is that for some a particular event might be life changing and for some the same event might be a nothing burger, for no obvious reason.
I agree with you that like the post I responded to that my response is too simplified. I also agree with the post I first responded to that we are, physically or mentally and emotionally, in at least some regards never in the same exact state twice.
To clarify my comment, I was attenuating to the causal progression of identity and referencing the physical dimension of that as it is less likely to dissolve into wasteful argument. Once we exist past a day boundary we don't get to be us today without an us yesterday. I admit that the lines of existence and self can be plausibly taken as very fuzzy and I don't want to debate any of that minutiae.
My point is that we are the intersection of what we are across all the domains of our being to whatever extent we exist at the times that we do. Confusing ourselves about what we mean by a person doesn't help.
You don't have to disbelieve anyone who says a certain aspect of a persons life typically has little influence on their later life. Another issue is that for some a particular event might be life changing and for some the same event might be a nothing burger, for no obvious reason.