I have to make a speech based on the quote, "A man can be destroyed but not defeated." -The Old Man and the Sea
I need a real world example of a person or group alive today or found in history that follows this theme.
I might point to Muhammad Ali as an example of a person who exemplifies the quotation. His physical prowess was, essentially, his career. Spinal damage took that prowess away from him (at least I think it is spinal damage and not a degenerative disease, but stories vary...). Despite his physical limitations, Ali continued and continues to appear in public and to inspire people.
I think this is true of everyone who has had to start over. In this economy, people have faced loss of their jobs and homes. They are not all giving up and sitting on the street. They are still trying.
I, too, think immediately of the Native Americans and particularly Chief Joseph's so-called concession speech. He is clearly a defeated leader who speaks with dignity and nobility in the face of absolute surrender. It's a short speech and would be a powerful example to use in your speech.
Here in the United States, perhaps the most famous example of such a person is the Revolutionary War hero Nathan Hale. This is the man who was hung for being a spy. On the gallows, he said that his only regret was that he had "but one life to give for my country."
This is an example of being destroyed (he ended up being killed, which is pretty much the ultimate in destruction) but not defeated (because he remained brave until the end).
It seems like the basis of your speech should be on the individuals or groups in history that have survived and endured, enabling them to enjoy some level of triumph. In my mind, I would point to Native Americans as one particular group that endured societal destruction. Their endurance today and the understanding of what they endured at the hands of American notions of "progress" serves as testament to how they were not defeated. In the end, there is a historical judgment against those who did wrong to Native Americans. While this might not necessarily restore all that was taken and endured, there is some level of solace that can be taken in the idea that they were not defeated. Their presence today reminds one of the cost and sacrifice involved in American History. I think that the same type of analysis could be applied to those who endured the Holocaust and the racist practices of the Nazis. In this setting, the same idea of being destroyed and violated is not automatically synonymous with defeat.