Arraya what you said about capitalism may be true however in nature there is an abundance of classes within pretty much every single society from species that form them. From ants to bees, to more complex societies of mammals, there are niches within those societies. Please don’t try to blame capitalism for everything. Furthermore within nature when species become weak, old or sick they die. There are no safety nets for them to enjoy.
As much as you love to bag on capitalism, nature is not the utopia that you make it out to be. Nature is a place where the strongest survive and the weak die.