What was the single most important point that Orwell was trying to make in Animal Farm?
I think that one of the most essential points that Orwell is trying to make is that citizens cannot afford to blindly follow and trust their political leadership in the modern setting. While Orwell features a great deal of venom and vitriol for Napoleon and the leadership of the pigs, Orwell is also fairly critical of the other animals for blindly trusting the pigs. Orwell believes that the citizenry that mirrors Boxer's faith in leadership is asking for trouble.
One of the single and most important points that Orwell makes is that when there is blind leadership in political authority, the grounds for abuse and tyranny are laid. Citizens have to voice dissent and criticize their authority figures at every possible instant. The ability for citizens to become politically engaged is vitally important for Orwell. Granted, when animals in the novel do speak out, they are killed by Napoleon. Yet, this would only underscore the importance of citizens learning to get turned on to politics before politics turns on them. In the end, Orwell's demand for citizens to become politically aware of their leadership is one of the most critical and important points that comes out of the novel. This is a reality that Orwell views as needed in both Communist Russia as well as "the West."