SPOILERS FOR BOTH BLADE RUNNER AND BLADE RUNNER 2049
The answer to OP's question is irrevelant to the main message of the movie, just like it does not matter whether the accused was guilty in 12 Anry Men. However, a potential answer, or lack thereof (meaning both are equally feasible) could enhance the movie. As in, if Deckard were a replicant, with Rachael being one, too, it would mean, that two replicants gave life. Replicants created by man created a man, as well, which makes them even to men in the biological sense. But to give life is nothing exceptional. So do thousands and thousands of species all around the world. However, it may be more special in the world of Blade Runner, especially for replicants that call it a miracle.
The main question the two films pose is "What makes a human?". What are some characteristics that are exclusive to humans? Is it free will? No. K had it all the time, but he did not realize it until he found out that he may be a human. That was the turning point for him. Most replicants were docile slaves, because they had been brainwashed and made believe they are not humans (meaning: worse).
Is it the act of sacrifice for another person? That's what 2049 is hinting at with K saving Deckard's life at the end. Then K lays down on the stairs, in the snow and dies. Blood seeping from his belly. Rain washes away blood, but blood stains snow. Memories washed away versus memories kept. If not by K, then by Deckard's daughter.
What made Roy Batty human? Was it his act of mercy towards Deckard? Or was it his mortality salience? The final realization of his own life's fragility. The moment when he realizes that his own life is but a tiny particle in the infinitiness of space and time. The fear of death and what happens after. The fear of being forgotten. The desire to be remembered, at least by one person. That's very human.
I think the introduction of AI in 2049, namely Joi, was meant to show how human replicants are. Joi may at first look like a human and behave like one, but in the end we quickly realize that she isn't one. Her awkwardly trying to synchronize with the prostitute's body movement, or calling K "Joe" were all (pre)programmed things. She was built of booleans, instead of DNA. She was pretty good at mimicking human behaviour at times (probably would've passed the Turing test), but her artificiality was apparent. Her biggest desire was to leave the confined space of K's room, to become free like a human, but the very moment she and Gosling's character are outside in the rain, we see rain pouring down Gosling's hands and pouring right through her hands. Then, she quickly notices it and makes it look like the rain is pouring down her hands as well. But it isn't. The more you think about it, the sadder this scene is, and even though the whole Heresque (Herian sounds more badass, though) AI subplot ostensibly ends the moment Luv stomps on Joi's gift, it really ends some time later, when Gosling is haunted by a giant 3D model of Joi - now more than ever remiding a sex doll. Just a programme. She is not human. She was programmed to be Gosling's girlfriend, so she is one. She is programmed to be the face of a filthy sex ad - so she is one.
But replicants have a choice. K made this choice. Even Luv, albeit a Schwarzcharakter to the very end, shows human emotions. She cries when she sees what Leto did to the new-born replicant woman. She cries when she kills Joshi. She cries, but she is not supposed to. Yet she does. Joi would have never cried, if she was not programmed to. Luv still does her job, possibly because she fears Wallace, or because, as she says during the final fight, she wants to be the best.
All in all, if it looks like human, feels like human, behaves like human, thinks like human and shows every characteristic of a human, then it is a human. If you were to spend the rest of your life with a replicant, I bet you would never ever realize he or she is not a human (unless he/she, or somebody else told you). Deckard does not care if the dog is real (that is, if it's "doggian"), just like you are not supposed to care if the owl in the first movie is "owlian", or Deckard himself is "human". He elevated above this. He is not trying to divide into humans and not (or sub)humans. And I believe audience should not either.
By the way, at the beginning of Villeneuve's sequel there are people throwing slurs at K just because he is a replicant. It was no different from real-life people throwing slurs at people of different race, skin colours religion, or sexual orientation.
Sorry for this long, incoherent mess. I hope that even though I may not have answered the question, you got something out of my post.
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Look, I'm not judging you - after all, I'm posting here myself, but maybe, just maybe, if you spent less time here and more time watching films, maybe, and I stress, maybe your taste would be of some value. Just a thought, ya know.