Acceleration is measured in units of distance per time squared, not distance per time.
If Earth was accelerating up at 9.8 m/s^2, and you jumped at a speed of 9.8 m/s when Earth was travelling at a velocity of 100 m/s, you would then be travelling at speed if 109.8 m/s. This would mean you are going faster than Earth and thus would start moving away from it.
However, Earth continues to accelerate and after 1 second is now travelling at 109.8 m/s. Thus you would now be moving with it, but some distance away.
After this time Earth will be travelling faster than you and thus you would be getting closer to Earth.
At the small scale you cannot distinguish between gravity and Earth accelerating upwards.
You can only tell them apart at the large scale, with gravity dropping off as you get further from Earth and varying over the surface of Earth.