First is Last and the Last is First - Quick & Clear Bible Study

What does the expression " the first is last and last is first" mean? Is there anything we can learn from understanding it?

Verses used in this study:
Mark 9:33-35
Mark 10:28-31
Luke 13:23-30
Romans 9:30-33
Romans 1:16
John 4:22,39-42
John 3:16