Harry Potter TV Series

St. Widge said
You know, I read the book and it seemed clear to me that Deckard was a replicant. Did Dick really say that he wasn't?

100%.
https://web.archive.org/web/20051230064849/http://www.devo.com/bladerunner/sector/1/philip.html

"The purpose of this story as I saw it was that in his job of hunting and killing these replicants, Deckard becomes progressively dehumanized. At the same time, the replicants are being perceived as becoming more human. Finally, Deckard must question what he is doing, and really what is the essential difference between him and them? And, to take it one step further, who is he if there is no real difference?

But there are clear indications in the story as well. The androids in the story can't feel empathy and they think that Mercersim (which was left out of the film entirely) is a scam. Deckard clearly feels empathy towards others, even the androids themselves eventually. He also experiences Mercerism and in the opening, he uses an empathy box, which we're later told the androids aren't able to use. Clearly, Deckard cannot be an android.

The ambiguity is on purpose because Dick is trying to point out that we as humans must retain our empathy or we have no more "right to exist" than the androids who have no feelings of concern for life forms other than their personal self. This is where Deckard is in wrestling with the fact he kills living beings as a vocation. Dick is using the androids as a metaphor for humanity's (at "the ruling class") maltreatment of animals and nature as a whole, and Deckard basically is humanity growing a conscience.