Oil is processed using fractional distillation, we're not making the kerosene, in some sense a fraction of the oil "was" kerosene and we just split that out from the rest.

It's not important that the kerosene was once a dead organism, we can technically just make it with energy, carbon and water, it's basically a narrow range of hydrocarbons so you synthesize a suitable mixture of CxHx chains and that'll work for e.g. the turbines in a passenger aeroplane. Today that's not economically sensible because you can just buy oil, but when the oil runs out, or we aren't processing nearly enough for other reasons already it could in principle make sense to literally do solar power + CO2 + water => kerosene.