What were the series creators trying to tell us in their story? What were the lessons we were supposed to glean from their tale?
In regard to the concept of time, probably an ancient philosophy over the modern industrial view. Ancient Greek and Roman thinkers believed that time itself was an illusion. Nature, and man being part of it, were part of seasonal cycles. The whole world was geared to cycles: seasons, tidal, celestial calendars that covered 24,000 year periods (which accuracy confirmed by modern computers). Ancient inventors made water clocks which help predict the star patterns and astrological events. The people of that time lived in the "now."
Only slackers, casinos and opium dens have need for just living in "the now" rather than being connected to other working individuals in society.
It was only when industrialization and railroad companies brought in "time zones," a division of the country into hour blocks in order to more efficiently move passengers and freight to long distance destinations. Time became a mathematical formula of set hours and minutes that was disconnected to the past agricultural sun dial observations. The mathematical time evolved into our normal cultural concept of linear time lines. Daily lives are now controlled by the hourly blocks of time. In fact, in some sense, we are slaves to time periods just as Desmond was a slave to imputing the Numbers into the Hatch computer.
In the sideways world, Christian tells Jack that there is "no past, present or future" only "now." Everyone in that existence was dead. Souls have no need for linear time frames. They are eternal.
The island was sort of a time transition zone. Once the 815ers arrived, no one really counted the days that they were stranded on the beach. The only key element of time was 108 minutes. After that element was eliminated, time became a logical illusion when people began to "skip" across different decades at random until the FDW was turned a second time. The true meaning of time may be that it is all in your head. That life is a cycle but you perceive your living time as an illusion.