The Matchlock had it's origins from a simple serpentine that first appeared on a picture of a Handgonne in 1411. The burning slowmatch was clamped into the serpentine freeing up the hand so that both hands could be used to aim the firearm.
By the later 1400's, true Matchlocks had appeared with the lever style appearing first. A burning slowmatch is clamped into the serpentine