If nothing ever changed there would be no time. Imagine looking at the objects in a room - if nothing ever changed even the hands of a clock would not move. The simplest form of change is the motion of an object. We say that an object is in motion because we observe that its position changes with time. In fact we invent the idea of time to account for the change in position.
Time consists of instants.
The instants differ from one another, however slightly, and this is how our impression of time arises. It is as if there is a cine film and we are looking at successive frames. If we imagine such a film laid out in a line it is clear that all frames coexist. There is no time, only position. The frames at different positions effectively have different times.