Jack Kennedy's father, Dave Kennedy, was born on Ebenzer Mission in 1883 and Kennedy was born on the Wimmera River not far from the Mission.
Kennedy did not have much schooling and he also did not learn much of his Aboriginal language because he would be beaten for speaking it at school. Kennedy went to work on local farms at the age of 13 because his father Rheumatic fever and a bad heart and could not work.
In 1940, while living in Antwerp, Kennedy joined the Army and became a Gun Layer in the Field Artillery. After discharge in October 1945 he was prevented from joining the regular army because of the racist policies of the Menzies government. Kennedy later worked on the railways at Pakenham.