The thing I find curious about time, is that if it is a dimension, we are fixed in speed of movement along said dimension. In the 3 spatial dimensions, we can move freely along them either way (jumping up and down means going both directions in the Y axis). If time is similar to the spatial dimensions, then that means that there must be a way to move along the timeline at different speeds (including backwards). The key thing is how similar the spatial and temporal dimensions are, and whether we'd ever discover the technology to move along said timeline.

About the Z-Axis. The thing that some people find difficult about the Z-Axis is that we only really see in 2D, but having 2 eyes gives us very limited 3D perception in the Z-Axis. If you close one eye, you have only 2D vision, but things don't look like they've lost a whole dimension, right? 3D on television screens are only illusions of 3D, just like 3D glasses give the impression of 3D. The human brain has learnt to work out how far away things are by their size. Maybe you've seen an advert where there's a car far away in the background, and a man in the foreground, much bigger then the car. Then the man picks up the car, and you realise that they were at the same depth all along, but the car was smaller than you expected, just a toy car.