What is the irony of the dead parachutist landing on the island?

The irony of the dead parachutist is that the message which should have reminded the boys of the real world was mistread and strengthened their belief in the imagined world of beasts. The arrival of the parachutist in chapter 6 is the message from the world of adults which Ralph had hoped for in the previous chapter. If the boys had seen him clearly they would have been reminded that there was a whole world beyond the boundaries of their island and they might have been encouraged in their efforts to try and get rescued. Ralph's position as leader would have been enhanced and his efforts to improve their lives might have gained more support. Unfortunately the parachutist was mistaken for the beast, which turned the attention of the boys inwards towards the affairs of the island. They forgot about the outside world and the need to be rescued, which undermined Ralph's position as leader. This reinforced Jack's attempts at gaining power to the detriment of them all.