Question

in what sense are men and women merely players on the stage of life

Answer 1

in the sense of their roles in life that played by theirs such as childhood, students, etc.

Answer 2

In these lines the world is compared to a stage in which men and women are merely players. Just like in a play players come on the stage do their part ang go. Similarly in a stage called world players ie men and women come they do their work assigned to them by God and they go ie they die and leave the stage called world.