Cherrylock
All the above is correct. Most, but not all, jet engines require more than one action to start them. Very simply, first you engage the starter motor & then when the engine reaches a specified speed you switch on the fuel & ignition (fuel & ignition only require one action). The starter motor will disengage automatically at another specified speed & the engine will continue accelerate to idle speed.
The starter motor is not usually directly connected to the front fan which is why you may hear the engine start before the fan rotates, if you are close enough you may even see the fan rotating back-wards at the beginning if there's a tail wind.