Time to do some diagrams of the area the lift jib needs to cover along with the highest and lowest end point positions. I too have a jib crane lift thingy concept on the go and currently having issues reconciling jib end positions and hoist mechanisms to get something that works well in all positions.
My take is that multi fall rope and pulley systems work well if you have headroom. Rapidly become something of a PIA at low level. As has been mentioned before multi fall systems have considerable inherent drag and may well not come down unaided unless decently loaded.
Hand winch systems tend to be easiest to use standing up with the winch around waist height. With a swinging jib you need either to pass the lift cable or strap through the centre of the pivot or have some sort of guide to stop it coming off the pulleys. Swinging a hand winch with the jib works with the winch on top but in other positions it can be hard to use. Personally I don't like cranking on something that isn't properly solid.
Dipping jib systems, as frequently used to lift in mobility scooters into cars, are very effective. Especially if you can be cunning about jib shape and pivot position. Probably the most versatile arrangement combines a dipping jib with some means of adjusting the cable or strap fall length. A proper winch is overkill. I'm looking at a ratchet strap mechanism for this job.
Electric power drive makes the design much easier. Whether via winch or using a battery drill turning a threaded rod to move a dipping jib. If you don't need a vast movement on the lifting eye a threaded rod and battery drill can be adapted to pull the lift cable or strap. Pass the lift cable or strap round a pulley so the length change is twice that of the nut movement on the screw. I guess maximum feasible length of the screw would be in the region of 4 ft.
Needs to be a simple hook on and go system. If you have to futz about with it to set up for particular jobs you will only use it in real emergencies once the novelty has worn off. If then! How do I know? Put my back out 4 times so far 'cos it was "too much faff" to use the lifting gear I have. Not helped by it being "too much faff" to sort out something really easy to set up and use. Chain falls and I beams in the workshop now. Car loading and outside jobs still a work in (slow) progress. Folding engine crane is "too much faff" personified.
Clive.