They are the entire purpose
In animals, but not in humans. In humans it is only part of the purpose. It is also for pleasure. Same with food. Both are an appetite. Both appetites, if not satisfied, can have bad results. Animals just eat for fuel. Animals have sex to procreate. In humans, that is only part of the formula. We also enjoy food and sex is much more than just the physical act.
It is why we are not to be as “promiscuous” as animals.
Read Song of Solomon. It is not about procreation. ;-)
we enjoy eating, true. but would there be hunger at all if eating did not serve a purpose? it may be made into an occasion of enjoyment, as it is human nature to ritualize what we need, but it's hard to imagine it if the body did not require food.
if we had to have 15 minutes of standing on our heads each day, we'd probably have some interesting rituals surrounding that.