According to the Oracle’s prophesy to Trinity, Neo was necessarily the One before he died.
Trinity acknowledged her love for Neo long before he died: “Everything the Oracle has told me has come true. Everything but this.” The Oracle told her “that [she] would fall in love with a dead man, and the man that [she] loved, would be the One.” At this point, she’s not convinced that Neo is the One, and Neo certainly isn’t dead, so she can only be referring to the fact that she loves Neo.
Trinity was in love with Neo before he died. The Oracle said that Trinity would fall in love with the One. Hence, Neo was the One, before he died. Unless the Oracle was wrong, in which case she could also have been wrong about Neo not being the One in the first place. Either way, Morpheus says “Try not to think of it in terms of right and wrong… She is a guide, Neo. She can help you to find the path,” and then later, “She told you exactly what you needed to hear…that’s all. Neo, sooner or later, you’re going to realize, just as I did, that there’s a difference between knowing the path and walking the path,” implying that Neo was the one all along regardless of what the Oracle said, and this still took place before Neo died. On top of that, there’s a difference between being right and telling the truth. No one ever said the Oracle didn’t lie. Who knows what she could have been thinking.
Even if you completely ignore this evidence, the Wachowski brothers clearly wanted to emphasize Neo’s one-ness before he was dead. Take the Cypher conflict as an example.
“If Morpheus was right, then there’s no way I can pull this plug. I mean, if Neo’s The One, then there’d have to be some kind of miracle to stop me. I mean… how can he be the One… if he’s dead? You never did answer me before, if you bought into Morpheus’ bullshit… come on! All I want is a little yes or a no! Look into his eyes, those big pretty eyes. Tell me… Yes or No?”
“Yes.”
“No! I don’t believe it!” <i>Cypher is killed by tank.</i>
I don’t know how it could’ve been made any more obvious. This is all straight from the movie.
Edit: By the way, your second and third points are both extremely wreckless assumptions.