Non Availability of Other Time Moments to Experience
Time taken as a dimension has another unique characteristic besides its direction (arrow of time), that differentiates it from the space dimensions. The latter are available to perception in all their extent, while for the dimension of time there is only one point available, the present moment.
To appreciate the difference, if time was like the other dimensions, one would be able to "look" in one direction and see all the past moments of the point of space on which he/she stands, and "look" in the other direction and see all its future moments.
So in this sense we resemble the Flatlanders of a 2 dimensional world who can only see one slice of a 3D object, its intersection with the plane of their world. We are Flatlanders as regards time.
Past and future moments of time have some kind of existence, but we only perceive one slice of it "at a time", the intersection of the time dimension with our 3D space as it moves along its length, what we term the present moment.