Ballard's "The Drowned Giant" speculates about a possible human reaction to a drowned giant. It is a staunch critique of human nature. In this world, there is no hysteric reaction to the giant. People are interested and investigate the massive creature, but there is no introspection about the origins of the giant. The authorities take little interest and end up letting the crowds do as they please.
I feel this is intended to demonstrate the crass, careless nature of people in reaction to real events. The fantastic nature of a massive dead body stirs the reader, but we would have a similar reaction to a beached whale, or a natural disaster. The story uses fiction to put it in a perspective we can understand.
The people of the story then take the giant's body and start to use it as a resource. They build structures with it or create attractions at carnivals. This shows a blatant disregard of the giant and his own existence.
This shifts the readers perspective because we can identify with what we are seeing. The body of the giant is relative to us and we can’t help but identify with it, imagining ourselves being used without regard for our own individuality.
If this is Ballard’s message I, personally, feel it is an overreaction, but I appreciate the crafting he used to get his message across. It’s a simple situation of flipping the perspective of the reader so we can see a situation in a new light.