The fire lance, created in China in the 10th century, was the predecessor to what would become the world's first firearm. The matchlock arquebus, centuries later, was the first to have a trigger.
The hand cannon was more of a cannon than a gun, in that many of the first ones were large and couldn't be activated by merely pulling a trigger. Two people were needed to fire the hand cannon - one person would hold it with 2 hands while another would ignite it.
A hand cannon
Lighting a hand cannon
“They were heavy and required 2 people to ignite it.”