Ultimately the point of the movie is "if he's a replicant, who cares?". Conceivably anyone in the movie could be a replicant, and ultimately it doesn't matter. What matters is that we can ask the question, not what the actual answer is.
And yes, it could very well have been a coincidence. Even after the final cut came out Harrison Ford still maintained that Deckard was a human, and that he'd played the role as if he were human, and that's how he interpreted the script.