Things will appear as they are going down a curve but its just how things disappear into the distance
No they don't. Even notbatman tells you that horizon rises to the eye level or some such bullshit. So how can legs of a person disappear within the length of a perfectly level football field?
Let's see this test done on an indoor basketball court. It's gonna be smaller but at least the feet should disappear, right?
And if you lie down on your side, and place your head on the floor so your eye is only about an inch off the floor, you have an even better chance of seeing the near horizon.
Better yet, set your camera on the floor, and snap some shots that show the whole floor, including the feet that you hope are chopped off. Then examine the photos and calculate how much of the rubber sole or heel was actually chopped off. You can take all kinds of pictures so that you can be sure that you aren't messing up.
EDIT: You will probably find that the floor, which seemed so flat from up at 6 feet, has waves in it.