Benjamin Button is a long movie, but each second is of equal importance. There are many themes; some dark, and some light. The movie is very sad, but really contains great material. The importance of loyalty towards your friends, loving each-other no matter the circumstances, and appreciating what you have are some base themes in Benjamin Button.
Benjamin is friends with everyone in his nursing home. He understands their situation, and feels compassion towards them. When meeting the captain of a ship, his friend tells him that the captain never pays. Benjamin did not care, and boarded the ship on his search for opportunity. He always visited his friends and family in the nursing home, whenever he could. He to to war with his captain, even though he was told to stay home. This quality of Benjamin exhibits loyalty towards people that he meets, and holds a high trust threshold towards strangers.
Benjamin develops a close relationship with Daisy from a very young age. Although he eventually leaves to start a life of his own, he writes postcards to Daisy whenever he visits a different place. Going back the the original concept of loyalty, Benjamin eventually develops an intimate relationship with Daisy. As he keeps getting younger, and Daisy keeps getting older, their love for each-other is never changed. She takes care of Benjamin, until his death as a small 'infant'.
You don't know what you have until it's gone, as the saying goes. Because of the unusual aging properties of Benjamin, he viewed the death of his loved ones from a completely different perspective than a normal aging person. When he is young in age and old in appearance, he is treated as if he has seen death many times. As he gets 'younger', he witnesses more death, and that is extremely traumatizing. Benjamin has to cherish everyone and everything in his life, before he becomes too young to appreciate them. It is an extremely difficult situation to deal with, and I would not wish it upon my worst enemy (not that I have any). Aging backwards is a horrible curse, and it will never happen to anyone (hopefully).