Does the acceleration due to gravity ever change?

I think since the person is falling through the air with a negative velocity and his/her acceleration due to gravity is also negative

you answered your own question, does the acceleration due to gravity ever change? Nope. Does any other force act to accelerate this person?(remember, to accelerate, you need a force!)well, in a vaccuum, no, you accelerate at the same rate foorrrrrever

but in real life(well, on our planet) you deal with wind resistance and drag and all that, which DOES exert a force that opposes the gravitational force, AND since the wind resistance force depends on your velocity, eventually you'll go fast enough that it's exerting a force just as strong as the gravitational force and you stop accelerating completely(for a normal full-sized human, about 120mph, belly-down)that's called terminal velocity