I'm not entirely sure which specific 'Jesus dead child friend story' you are referring to. There could be many stories in religious or apocryphal texts related to Jesus and children. It might be about an event where Jesus interacted with a child who had passed away or something related to the concept of life, death, and Jesus's teachings.
If this story exists in a religious context, it could signify Jesus's power over death. Just as he overcame death himself, he might have the ability to deal with the death of a child, which could represent the ultimate power of God.
Jesus is considered a friend for sinners because of his unconditional love and willingness to forgive. He offers salvation and a path to redemption for those who have strayed.
First, make sure to use simple words and examples that the child can relate to. Focus on the positive messages and acts of kindness. Maybe tell it like a bedtime story with a gentle tone.