How is leadership shown throughout the story Animal Farm?

George Orwell's Animal Farm demonstrates the rapaciousness of leadership when it is provided power.

This is the irony of Communism: While its ideal is worthwhile, human nature is such that it really does not desire equality with all; therefore, corruption of the ideal occurs. The animals revolt against Mr. Jones who is despotic only to have their truly socialist leader (the ideal=Snowball) replaced by a dictator (corruption of the ideal=Napoleon) who is far crueler than...

George Orwell's Animal Farm demonstrates the rapaciousness of leadership when it is provided power.

This is the irony of Communism: While its ideal is worthwhile, human nature is such that it really does not desire equality with all; therefore, corruption of the ideal occurs. The animals revolt against Mr. Jones who is despotic only to have their truly socialist leader (the ideal=Snowball) replaced by a dictator (corruption of the ideal=Napoleon) who is far crueler than Mr. Jones.

During the progression of the narrative of Animal Farm, once Snowball is ousted and Napoleon takes charge, tenets of the Seven Commandments are gradually altered until they are reduced to virtually nothing and the animals live under the dictatorship of Napoleon. Symbolizing this erosion of equality for the animals and totalitarianism is Napoleon's progressive acquiring of the traits of Mr. Jones, such as his drinking, sleeping in a bed, and, finally his walking on two legs. 

The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which.

The acquired human nature of the pigs is what defeats them because it is the human trait of cupidity that propels Napoleon and Squealer to seek absolute power, which history proves is always destructive.