I am thinking it's possible that the same denarius that everyone gets at the end of the workday may represent that GOD loves us all the same. Everyone gets the same coin, GOD has no favorites. His love is equal to everyone and that does not change under different circumstances or the amount human effort. There is no amount of works we can accumulate to make GOD love us more or to 'earn' a greater reward from GOD.
The rich young ruler before the parable is told (chapter 19) can be a representation of someone who is first in this life based on human effort and accomplishments. His great accomplishments that are sown into his own life, and not into the kingdom of GOD, will not be rewarded in Heaven. The first will be last. JESUS also says that those who give what they have to the service of GOD's kingdom, will be rewarded a hundred times as much as they gave up. (Plus eternal life in Heaven) The last will be first.