I also seen quoted from the Jerusalem Talmud that a person’s body will decay by 120, although his body may continue to function a bit longer than that (especially with modern medicine).
See likewise Pirkei Avot (), which is even less forgiving: “At Ninety to be bent over; at one hundred it is as if the person has died and passed and is ‘nullified’ from the world.” Based on this, it is definitely possible a person could live a bit longer than 120.
For example, your worry about your brother's serious illness is pre-eminent and has displaced all other worries, because they all pale in comparison.
God recognized that man was sinful because the antediluvian lifespan was so great.
The average person, knowing he had so many centuries to go, did not fear death and his ultimate encounter with God.
Then going from Abraham to Moses, they went from the upper 100’s to the middle and lower, down to 120 with Moses.
In terms of later people who lived slightly longer, the commentators are not especially bothered.
Moses lived till exactly 120 (Talmud Sotah 13b) – and on top of it the Torah attests that his energy and vitality did not diminish in the slightest before that time (Deut. We thus bless people today that they be granted the same long, productive life of our great teacher Moses.
(See also Talmud Chullin 139b which sees a hint to Moses’s future lifespan in the 120 years mentioned before the Flood.
He had many years to live and enjoy himself first, with virtually no sense of his mortality.
Alternatively, life is such a struggle between man’s body and soul, that with so many years to live, a person is bound to succumb over time.
In truth, most of the commentators (Targum, Rashi, Ibn Ezra, Ramban, Radak, R.