The entirety of the novel explores the themes of leadership and power as we watch Napoleon corrupted by and disobeying the very principles he and the other pigs instituted to rid themselves of a ruler (like the one Napoleon eventually becomes).
Chapter one demonstrates the beginning of the fall of one leader or the power of one as he (Mr. Jones) stumbles through his duties because of his drunkenness. This demonstrates that a leader can easily become unaware, which is indeed what happened when the last ruling Romanov was in power.
As Old Major shares his vision, he does so with the idea that he won't be around long and that his idea is not necessarily for himself, but for a future. A good leader is a persuasive one. He had planted this idea, the animals almost subliminally took hold of it and before they know it (chapter 2...) rebellion has begun.
Old Major may have been looking out for his own, but the problem of leadership comes when one who seeks power just for the sake of having power doesn't think about all possible consequences.
Reading some of Thomas Jefferson's writings will show consideration that went into the idea of power to the people and the corruption of mankind. Could an evil leader rise in America? Is it possible? Very.
Orwell positioned this speech of Old Major's in the beginning to cause readers to consider the power of leadership. Should you follow someone blindly just because there is promise in their words, or should you check their motives, history and background before positioning them with such power?
The way Old Major demonstrates leadership in the first chapter is similar to the idea of power and leadership which will be enhanced throughout the work. As Old Major leads, he hopes to transform what is into what can be. This helps to demonstrate the critical element of leadership present in the novel. Namely, that individuals in the position of power must be willing to do what is needed to convince others of the authenticity of their own vision. Old Major is quite persuasive to the other animals, and his vision is one that allows itself to be appropriated by Snowball and Napoleon later on int he work. The notion of leadership presented is to be able to provide enough in terms of connection to allow others to accept the vision of what can be from what is.
Do you really mean that this answer is only about Chapter 1? I do not think there is very much there about leadership and power -- not nearly like in later chapters.
In Chapter 1, the only leadership shown is being exerted by Old Major. He is showing leadership by trying to get the animals to rebel against the humans.
In this chapter, leadership seems to consist of being persuasive. Old Major is able to lead because he is able to show the animals why their present situation is unjust and what a better society could look like.
So, in this chapter, leadership is the ability to inspire others to see things the way that you do.