When I first watched Blade Runner, I went in knowing I was supposed to wonder if he was a replicant or not. Turns out that I didn’t care either way. 😕
I don’t think he was originally intended to be. We know that Tyrell was. It is an interesting idea that the confirmed synthetic human is becoming more human because of his impending mortality and the death of his friends balanced against the supposed natural born human mechanically killing creations so human that he falls in love with one. The possibility that he might be artificial adds something to Roy’s taunts and Rachel’s questions about her memories and Deckhard`s profession. Making it obviously one way or the other was a mistake.