Man's lifespan length changed?

Adam, the first man, lived to be 930 years old. Methusalah, in the bible was the son of Enoch, and was the father of Lamech, and the grandfather of Noah, lived to be nine-hundred-sixty-nine years old (969). He was the longest life recorded in the bible. However, in Genesis 6:3 we are told that, "And the Lord said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years" and in the Book of Mormon we read in the book of 2 Nephi, chapter 2, verse 21, "And the days of the children of men were prolonged, according to the will of God, that they might repent while in the flesh; wherefore, their state became a state of probation⁠, and their time was lengthened, according to the commandments which the Lord God gave unto the children of men."

Is there a contradiction in that?

If Genesis 6:3 is a countdown to the flood, Methuselah's long life ends right before or when the flood begins (some believe the exact year). After the flood, lifespans significantly shortened. Noah's son, Shem, for example, lived for 600 years, a considerable decrease from his father's 950, Abraham's father, Terah, lived to be 205, and Moses only 120. From Shem (600) to Peleg (239): lifespan is nearly cut in half. By the time of Joseph (who only lived for 110 years!), lifespans are well below 120. Around the time of Eber to Peleg (5–6 generations after the Flood), lifespans fell below 500 years and never rose again. The nine disciples of Jesus Christ, in third Nephi in the Book of Mormom, other than the three Nephites who desired to live on Earth until the Savior returns, lived only to "the life of a tree", or in 3 Nephi 28:3 or seventy two years old. Today, in the year 2025, the life expectancy of man is 73-74 years old. The decline in human lifespans after the Flood is gradual, not immediate.

So, the truth is: each and every man or woman lives until they've been fully tested, that they can then finish preparations in Spirit prison or Paradise (see Alma chapter 42)...

And, there you have it...

JPS