I would argue we have a whole list of purposes:

• procreate
• copulate
• mate
• engage in sexual reproduction
• propagate the species
• reproduce
• conceive life
• bring forth offspring
• weave new generations
• kindle the spark of life
• sow the seeds of tomorrow
• whip up some womb-biscuits
• bake a bun in the baby oven
• start a stork-summoning ritual
• do the chromosome cha-cha
• know each other in the biblical sense
• lie together
• hook up
• get it on
• do the deed
• bump uglies
• initiate a genetic merge request
• fork the DNA repo
• compile the next generation
• instantiate another human

I think you got the gist.

And in the meantime also entertain ourselves, of course.