If you go to Singapore or Amsterdam or Seoul or Buenos Aires or Islamabad or Johannesburg or Tampa or Istanbul or Kyoto, you'll find that the people differ wildly in the way they dress, in their marriage customs, in the holidays they observe, in their religious rituals, and so on, but they all expect the food to be under lock and key. It's all owned, and if you want some, you'll have to buy it.
Because we imagine that we are what humanity was divinely destined to become, we assume that our prehistoric ancestors were trying to be us, but just lacked the tools and techniques to succeed. We invest our ancestors with our own predelictions in what seem to us primitive and unevolved forms. As an example of all this, we take it for granted that our religions represent humanity's ultimate and highest spiritual development and expect to find among our ancestors only crude, fumbling harbingers of these religions. We certainly don't expect to find robust, fully developed religions whose expressions are entirely different from ours.
Diversity is a survival factor for the community itself. A community of a hundred million species can survive anything short of total global catastrophe. Within that hundred million will be thousands that could survive a global temperature drop of twenty degrees which would be a lot more devastating than it sounds. Within that hundred million will be thousands that could survive a global temperature rise of twenty degrees. But a community of a hundred species or a thousand species has almost no survival value at all.