According to theoretical physics, time as such does not exist, or rather is an illusion generated by limits of causality and locality. We often conceptualize spacetime as a linear bar upon which we "move forward," but spacetime event as such is the entire line. The "movement" is an illusory consequence of the limits of information transfer constant "c" upon our mind. I have even encountered hypothesis that posit that "causality" is also an illusion and the only aspect of reality is locality.

I think there is a new book on time by a journalist, who amusingly thought to research a "light" topic for his next article. You are absolutely correct in the conclusion that time is not defined, understood, or proved; yet, no sane man would declare that time does not exist. The paradox of life . . .