EDIT: To give a bit more context, in 3D geometry, isometric (and other orthographic projections) are just projections which do not apply a perspective divide. No time component anywhere.
Normal 3D perspective has a vanishing point, objects appear farther and farther in the Z axis. Distance is directly related to time in our heads. Isometric perspective eliminates that notion, objects at the back are the same size (and as “reachable”) as the ones in front.