I asked this question years ago, as an extra credit question, in a Physics test. I asked the students to consider only the effect of the gravity. More than half answered that “you would fall out the bottom of the hole”, while other answers ranged from “you would not fall into the hole if the tunnel was dug parallel to the equator” to “who cares?” As the Physics teacher, it was a very humbling moment.
How do we know that atmosphere plays no part in falling, only mass below?
I asked this same question to a physics instructor when I was going to college.