Time did not exist.
It was the motion of matter that let humanity sense time; it was the growth of all things that let humanity sense time; it was the cycle of spring, summer, autumn, and winter through the four seasons that let humanity sense time. It was a physical quantity humans used to describe the motion of all things.
Humans said that an electron experienced time when it transitioned from one state to another. They said that a planet experienced time between two different positional states as it moved around a star. They said that time had passed from the state of the universe at the Big Bang to its present state.
Among the stars, the waxing and waning of sun and moon had long since lost their reference points. Humanity's time could only be defined by the completion state of the things they did themselves.
The void was vast, and all around was desolation.
There should have been no concept of time, but in order to better describe the changes of all things, humanity still followed its own senses and placed the physical quantity of time into various scientific systems to describe the universe.
Without time, there was no such thing as time flowing backward.
And yet humanity still said that the Time Dimension ran through the macroscopic spatial dimensions, and also said that time was transmitted in different ways and states across different Microscopic Dimensions. For example, when studying microscopic five-, six-, seven-, and eight-dimensional space-time, the temporal state humanity needed to describe was Tubular Time; nine-dimensional space-time was Membrane Time; ten-dimensional space-time was Three-dimensional Time; and by the time it reached the four macroscopic space-time dimensions, time was Linear Time.
Why were there different descriptions of time? Because only by using different methods of describing time