So how is that kites can fly?
Kites aren't aeroplanes. They are anchored to the ground by their string and so, 'feel' the wind in the same way a groundbound object does - so the wind gives them airspeed just as a boat anchored in a current will have speed relative to the water even though it isn't moving relative to the river bed.
Let go the string, however, and they become 'aeroplanes', no longer ground-bound. They'll immediately cease to generate lift as they lose all airspeed and move with the air (the wind) rather than through it, and flop along falling out of the sky some distance downwind of the person who was previously holding the string.
This is all really basic stuff any student pilot knows but a groundling might not... Like others, I suspect a leg-pull here.