Giant
Giant is a complex character. Due to his physical attributes, it is easy to take him as a brute and he feels more comfortable leading a lonely and secluded life. However, he is not devoid of compassion as is shown by his gesture to the little boy.
His heart melts to see the kid in distress and helps him up the tree. He falls in love with the innocence of the kid and his heart aches to meet him again.
In the end, he does meet the kid but only to find him waiting to take him away to a different world. The Giant dies in the comfort that he could finally be at peace and closer to his little friend.
Boy
The boy is of tender age and short stature. He is unable to climb the trees and feels sad due to it. But he is innocent and lacks fear for the giant. When the giant helps him up the tree, he kisses him and shows his gratitude.
He is gentle and compassionate and does not judge others in appearance alone. In the end, he returns to take the giant with him to the next world where there will be no isolation, sadness or injustice.
Other Kids
All the other kids are shown as a collective of boisterous and mischievous bodies of energy, they are scared of the giant and his brutish appearance but they are attracted to the blossoms of his garden.
The lure of open spaces to play is too much for them and they break into the garden to have playful time. After the Giant’s change of heart, they accept him as a friend and spend many days playing and having fun together.
They can sense the giant’s sadness as he asks them for the little boy and try to locate the little boy but to no avail as he was an outsider to their group.