Time is a temporal dimension, not a spacial dimension.

A dimension is simply an axis across which you can measure. Moving through a spacial dimension is a fairly simple concept, but moving through a temporal dimension becomes a tricky idea.

Why? Consider your units:

    When moving across a spacial dimension, you have spacial units / temporal units. feet/second, meters/seconds, etc.

    When moving across a temporal dimension, you have temporal units / temporal units. They appear to cancel.

How can this be interpreted? Either there's another time dimension outside of our current time dimension to provide the units in the denominator (and another to provide units for it, and so on), or temporal dimensions are not the same as spacial dimensions.

You can bring your multiple-observer math into this all you like, but that only gives relative speed and relative units. You're still dividing time by time and getting a ratio rather than a speed.

So you can all continue with your lives, time does exist, time is a dimension, just not a spacial dimension. The phrase "moving through time," however, seems to be of questionable meaning.