Humans can accidentally start fires many ways, such as generating sparks, electrical, heat, a cigarette or match carelessly dropped, a glass bottle concentrating the rays from the sun, a camp fire, etc- - -
As a Boy Scout, I cannot remember ever starting a fire with a spark or friction bow. Maybe made smoke with a magnifying glass.
I did see it done by instructors.
But, yes, sparks and stuff can start fires.
Yes, and Murphy's Law says that when you need to start a fire it is really hard.
When you don't want a fire to start, it is really easy.