Well your purpose may just be to satisfy animal urges but some of use are here to have spiritual journeys and experience what this physical reality has to offer. If you want to limit your reality to that of natural instincts cool just don't put that on us who live for more than eating sleeping and procreation.
the purpose of life is to give life purpose, and reproduction is a huge part of that agenda.
be fruitful and multiply (Genesis 1:28)
God didn’t intend Adam and Eve to have children just to have children. In the remainder of Genesis 1:28, we see a useful and desired result: to “fill the earth and subdue it, and have dominion over the fish of the sea and over the birds of the heavens and over every living thing that moves on the earth.”
if your not having children the next best thing to be doing after is to be serving your creator.