The meaning of life is to not know the meaning of life. As simple and bland as that may be that is the answer. Whether that means you make your own meaning from there or that it can have a different meaning ( an absolute one, to you, or others) is another question in itself which falls UNDER life's meaning...which is not to know a meaning.
So you have an answer and a question (which can't be answered) simultaneously: We cannot know the meaning of life and in regards to that, does it still have a specific meaning or meaning of some kind that we cannot know?
So in essence, the question we want to know should be "why can't we know?" and there are too many questions and contradictions that would come from any reasoning concluded or the actual meaning is beyond our comprehension.
It is not that we all need to be in agreement for the meaning of life to hold true. It is that if that meaning truely is fact it would have to hold true to every person. For this to occur, all would have to be right, some would have to be right, and none would have to be right all at one time.
It is only in not knowing a finite absolute answer that any meaning can really hold true.
For someone to be proven right....that would mean someone would have to be proven wrong.
For someone to be proven wrong, there must be someone (or something/s) to possess the knowledge to know something to be correct.
Because we cannot attain the knowledge to prove someone right or wrong...all possibilities must exist in this present state...which is time continuing. All meanings must exist, some, one, and none.
Only through no one having knowledge of the meaning of life are all these things possible at the same time.