A key puzzle raised by Blade Runner is whether we can definitively distinguish between real humans and artificially engineered replicants. Suppose that no test (either objective or subjectively introspective) could show this for sure. Would that mean that a given replicant was indeed fully human?

Yes, because from the movie, it appears that we cannot so easily delineate what it is and what it isn’t to be human, except through testing (which would be scientific in approach

Explanation:

Blade Runner is a movie which is an adaptation of a science fiction novel by Phillip K.D titled "Do Andrôids Dream of Electric Sheep?" set in the year 2019.

Blade Runner’s most philosophically questions centered around what it means to be human, how do we define ourselves as humans? Do we define ourselves solely on the biological characteristics, or is there something more that makes a human?

Hence, from the movie, the replicants shows most of the characteristics of human, especially in intelligence and empathy, but not biologically.

Therefore, it can be concluded that, we cannot so easily separate what it is and what it is not to be human, except through testing (which would be scientific in approach).