I think the sensibilities of the human species calls for answers and reasons for those things seen but not understood and those things unseen but felt.
Going way back to the Neanderthals there is burial evident of preparations made to help the departed deal with what's next.
In every civilization one sees a belief system in place both that can be primitive or complicated. Rational and not rational.
The rationally is that this life is but one level of our existence. So within every race or tribe you have a sense that there is a Next.
To explain this next stage there are rituals and holy men, witch doctors etc. who can develop the concept into something workable and by their rules and traditions.......understood.
Their is no Culture in all of history that didn't have some form of religion or a belief in their gods..
As we learn more about our humanity the superficial belief systems are failing each in their own way. Today's religion may just be today's religion.