well, according to many old stories human lifespan can be upwards of 800 years, there is knowledge of how that happened that has been long lost, probably partly washed away in the Flood, it's notable that it was said not long after that, that the lifespan would max out at 120

whatever it was that enabled that, will be rediscovered one way or another... i firmly believe that it's not analogies or word games with calendars, at worst you can say a year was 360 according to old hebrew books but that's not like saying a year is a day or a day is a thousand years