Is there a meaningful purpose of human life ?

Why were we born ? Is there a duty (or duties) for us human ?
Were we born just to consume, to excrete, to sexually mate, to sleep ? Just to do these 4 main activities every day for a few years and then die ?
If that is the case, then how do humans differ from non-sapient animals ? Non-human animals also have those 4 activities.

I was informed from my teachers (Buddhist monks) and books that we have the main duty to develop our mind, in order to elevate its moral quality. When the mind is developed, it will be happier, more and more.

The purpose of Buddha's teaching is to lead humans into having happiness, from elimination of suffering inside the mind, regardless of their physical environments. If lay-persons and Sehka persons (i.e. the 3 classes of the developed ones, except the Arahanta) keep on developing their minds, they will become less-suffered from all worldly experiences they face in their lives. The state of ultimate happiness that a developed mind can experience is Nirvana, a Sanskrit term (also called Nibbana in Pali term). Sekha persons can experience Nirvana briefly, mainly during meditation. Arahanta monks can experience it anytime they want, not even a meditation is needed. That is according to words of a teacher of mine.