Survival of the fittest does not mean what you think it means. It means the species who fit the environment best who survives, in the context of evolution and a species becoming instinct. For example, in a post nuclear war scenario, cockroaches are better fit to survive in a nuclear winter than humans. It is not even about inra-species conflicts.
Intra-species lethal violence is practically non-existent even in non-human species.
Government is not "what society has created". And it does not "protect the weaker members". That simply is an illusion. The poorest %10 of the population in a free market country is better off than average person in a big government socialist or communist country.
"The elected representatives are vested with more power because people have granted it to them."
You cannot grant anyone else something you don't have. If you do not have the right to extort money out of your neighbour by threats of violence, with the lie that you will protect them in return (it is called extortion or protection racket if non-state organizations do it)
Please tell me, how well the state worked to protect their people, when the state turned against their own people, killed their own citizens in democides. 263 million people have been mass murdered by their own government in 20'th century alone. This dwarfs even how many people of other countries governments killed, in 2 world wars (around 100 million).
https://www.hawaii.edu/powerkills/20TH.HTM
Please tell me, if governments protect the weak against the strong, who protects the weak from their own government?
There is very little difference between what you call "representative government" and "military dictatorship". Look at the democide list. They have all risen to power by democratic elections, in a representative democracy.