Jack was set to embark on a new chapter in the military in 2021.
He had completed his final year of secondary school at Kelston Boys' High School in 2018, having previously attended Wesley College.
The family had moved to New Zealand from Fiji when Jack was about 7.
While the tight-knit family mourn, Heritage has been moved by the sheer number of people showing up their home to personally pay tribute to Jack's memory.
His "kind-hearted" son made friends with ease.
Even as Heritage spoke to the Herald another friend had arrived to pay his respects.
"It has consoled us," he said of the overwhelming level of support.
There were many young people among those grieving.
"I have been telling them; 'I wouldn't want your parents to go through what we are going through now'," Heritage said. "It is so painful."
Family described him as a naturally gifted sportsman who loved rugby.
He was a former NZ Māori under-18 player, who played for a New South Wales country team last year, before coming home to play in the Waitematā Rugby Club's premier team.
As a roofing apprentice, he was working hard towards completing his trade training to provide for his young family.
"Our world has been turned upside down and inside out. This is supposed to be a holiday season of festive happiness, and instead we are weeping and we are grieving."