Jack cannot kill the pig because he is an innocent boy who wouldn't kill a living creature.
Jack is unable to kill the pig, due to his fear of the squealing and blood that the pig would produce. Jack's inability to kill the pig is a symbolic example of the still existent human moral within the boys. Jack being unable to kill the pig shows he is hesitant to kill others, because he believes it is wrong.
because the pig was stupid
Jack claims he only needed barbs on the spear head to kill the pig. Jack is consumed with killing a pig, but is unable to do so.
He was too innocent to kill, but later in the book he lost that innocence
This yet another example of something which is not a question but is in fact an assignment set by your teacher for you to complete.
He will get a pig next time he goes out.
He was at first unable to kill the pig because he was still a kid who didn't know savagery and therefore couldn't kill the pig but later on when he does kill the pig he becomes "bloodthirsty" and always wants to kill and overpower everything and everyone.
to kill the pig
As Jack talks about the pig, he becomes increasingly excited and aggressive, gesturing wildly and using violent language to describe how he wants to hunt and kill the pig. This shows his innate inclination towards violence and savagery.
Jack and Roger planned to hunt and kill Ralph as he was the last remaining obstacle to Jack's authority on the island. They intended to use force and violence to eliminate Ralph and solidify Jack's leadership among the boys.
Ralph is initially uneasy and disturbed by Jack and the hunters' savage behavior during the pig kill. However, he ultimately participates in the ritualistic dance with the others due to the primal energy it invokes.
Jack doesn't kill the trapped piglet because he wants to continue hunting and believes that a live pig would provide more excitement and challenge. Additionally, Jack may not see the trapped piglet as a worthy target for his aggression.