Trying to give an honest, unbiased answer to the question, not influenced by my opinions on the movies:

ANH: Anyone can be a hero.
ESB: One must learn how to deal with failure.
ROTJ: Everyone has good inside them.
TPM: Coincidences can result in enormous change.
AOTC: Evil can sometimes hide in plain sight.
ROTS: Too much attachment results in greed.
TFA: Evil will always return, but so will good.
TLJ: The old ways are flawed, but they still have value.
TROS: Friendship can be a powerful ally.