Elaborate on what? The themes?
They deal with failure, heroes, hope, and myth. The interesting thing is they aren't at all distinct in the film but all tied together. It shows us that heroes aren't perfect they fail and struggle as they are just human and don't live up to the myths they inspire. And yet, those myths do have merit as they inspire hope as we see in that last scene. It's relatively complex stuff for a SW film (SW films have always been rather shallow so it isn't saying much) and certainly stuff that we haven't see before in one.