I never said chimps weren't afraid of death, but last I checked, they weren't teaching Sunday School classes. No other creature depends on spirituality to cope with death and the other mysteries of life. In fact, they seem oblivious to death, the unknown, the unexplained... they don't really seem to care, but humans can't cope with it and have to 'invent' spirituality... it doesn't make sense to me.
I'll ignore the fact that you did say chimps weren't afraid of death. The reason they're not teaching Sunday schools has a lot to do with the fact that they can't build them, and that they really don't have teachers in general or any kind of buildings. There are reasons for that, and for the fact that man does. An advanced cerebral cortex is one of those reasons.
You do understand that we're different from most animals in reasoning ability, correct? It's not just spiritual issues. It's how to fix a car, too; oh....and how to BUILD a car, as well. And make fire, and make a wheel, and play basketball, and contemplate retirement...pretty much everything.