The simple concept of sacrificing one to save many that most christians have is not that difficult to grasp if you look at it like a religio/philosphical 'trollycar dilemma" kind of thing but this particluar understanding of a 'ransom" JWs have I always found to be even more convoluted, confusing and problematic.
It opens up a whole heap of other logical questions like who pays the "ransom" to who etc. If the ransom has been paid once and for all time doesn't that mean everyone is atomatically saved? If not why is there other "payments" on top of the "ransom" in the form of obedience to a modern corp/org? If the ransom was paid in full why is there other payments on top of the "ransom" like preaching and meeting attendance etc? I could go on as I had years of boring meetings to sit through and mull over this crap.
But, surfice to say it sounds more like a perpetual hire purchase scheme to me aka extortion and a perfect excuse for control.