Although Methusela is credited with having been the longest living man in history, it is thought that it was a mistranslation and that he may have died just before he turned 97

Methusela was the longest living man in history, according to the Hebrew Bible, and he grew to become 969 years old before he died seven days prior to the great flood.

Many have questioned the possibility of growing that old, and many explanations have been offered.

The ones that make the most sense and carries the most weight, are the ones that explain that there was a mistranslation and therefore a misinterpretation of how time was measured back then.

One of the theories is that 'lunar months' have been translated to read years. If that is correct, then Methusela would have died at age 78. The problem is that Enoch would then have had to have fathered Methusela when he himself was only five! That does not seem credible.

Another theory is that the Septuagint Genesis 5 numbers are in tenths of years. That would mean that Methusela died when he was almost 97. Enoch would then have been almost 16 when he fathered his son, which certainly is more feasible than becoming a father at age 5.

Whatever the argument or explanation, Methusela's name still gets used today to describe anything that is exceptionally old.

(Source)