The answer everyone missed: boundary layer. Air has friction. When you sit there, a boundary layer of much slower moving (relative to the motion of unobstructed

The answer everyone missed: boundary layer. Air has friction. When you sit there, a boundary layer of much slower moving (relative to the motion of unobstructed air as connection occurs) air creates an insulating effect around you. The fan removes the boundary layer by blowing it away. This effect is why food that is boiled cooks so much faster than food at 99C. You’d otherwise expect it to cook only a little over 1% faster but the actual effect is far greater. The boiling churns the water and disrupts the boundary layer. Similar principle in a forced convection oven.