I think that one of the most profound lessons that comes out of Orwell's work is the idea that those in the position of power can abuse their authority. The book resonates quite clearly with the idea that all power can contain an element of corruptibility. It is up to societies at large to create checks and balances so that such power cannot silence voices at will and become unchecked and unrestrained in its reach. It is here where the novel teaches much about life. Power in all forms is shown as something that necessitates limitations and institutional forms of limitation of reach. The notion of providing more opportunities for individual voices to be acknowledged is something that also emerges from the narrative. In this, Orwell is demanding that individuals not demonstrate blind loyalty to any realm where there can be complete abuse of power. Boxer becomes more of a cautionary tale about what could be the end result of total devotion and a lack of questioning on the part of citizens. In this depiction, the novel teaches that the need to question, to raise doubt, and to continual exercise and activate freedom to dissent at all possible moments is something that must be embedded within both society and individuals to ensure that such abuses of power do not happen with such stunning frequency.
The lesson that I take from this book is largely a political one: Authority is easily abused.
Corruption, however, is not automatic. It's gradual and that is a life lesson, I think. Napoleon and Snowball both began to take advantage of their position early on, but it took quite a bit of time before Napoleon began to wear human clothes and walk on two feet.
There was time to stop him. Action could have been taken. One moment of inaction, however, led to another as the animals of the farm chose to turn a blind eye to what was actually happening. Perhaps this suggests another comment on life and people: We see only what we want to see.