Between the period when written accounts of history at least aspire to modern standards of truthfulness and to recounting what actually happened, and the prehistoric period, there is an era of legendary history. I include in the legendary history corpus, for example, the Bible, the Avesta, the Rig Veda, the Illiad, the Icelandic and Norse epics, the Sumerian epics, the tales of King Arthur, the Medieval Lives of Saints, and a host of Chinese legends.
These stories blur the line between history, historical fiction, propaganda, and purely fantastical story telling. They recount the lives of heroes, of magic, of monsters, and of divine intervention. But, they also intersect with places, people and events that existed in history.
The Minotaur as a mythical monster surely never existed, but the Palace of Minos and systems of tribute and conflict with other palace-states and city-states in the Aegean surely did. Solomon really did have the mines he was created with having, but his story also contains hyperbole and pure inventions. There were blood feuds in early Norse and Icelandic society, but not sea monsters in caves and marshes to slay. There were English courts caught between a pagan past and a Christian future in England around the time that the Arthurian legends are set, but no real magical spells. The Philistines may have been taller than the Jews, even though they were not truly "giants." There were Messianic movements seeking independence for Jews from the Roman Empire in a more just and more Jewish regime, but if there was a Jesus, the Bible's accounts of his ability to perform miracles is greatly overstated.
One fairly common conceit in legendary history is an era of long lived men, the rulers of the land or leaders of the tribe, at the very at least, with the classic biblical example being Methuselah. Similar accounts appear in the Queen lists of the Kingdom of D'mt in North coastal Ethiopia and Eritrea, where just four queens purportedly presided over a Kingdom that lasted at least four hundred years, and in the earlier entries of the Sumerian king lists that may have informed the writers of the Book of Genesis.
What was going on here?
There are several plausible explain these impossible accounts, and all seem plausible to me.
One is that there may have been a tradition, reinforced by Kings often taking the names of their predecessors, of treating all rulers in a single hereditary dynasty as a single individual. Just as we talk about the dozen Dr. Who's or the half dozen James Bonds, there may have been eight or ten Patriarch Methuselah's. At the time the early king lists (the earliest of all historical records) were made, it might have been clear that a reference to one individual living 800 years was really a reference to all of the people in that dynasty who assumed the role over that length of time. But, that distinction may have been lost in the retelling until some people believed that it was actually true.
Another possibility is that there is a disconnect in units. For example, genealogies and king lists may have originally been kept in terms of months or tenths of years of service, then months of life, then years of life, then years ruling, with the change in units omitted in the retelling at some point. This falls within the scope of what Wikipedia describes as mistranslation.
A third possibility is pure hyperbole, perhaps for purposes of propaganda. The men of old were great. Their achievement were exaggerated. And, in the oldest accounts, where almost nothing survives to the present but their names, order of appearance and ages, the best we can do to inflate their importance is to inflate their ages, a process that continues until the oral tradition is reduced to writing. Closely related is the notion that the time periods may have been symbolic in some kind of numerology.
A fourth possibility is gap filling. Perhaps it was widely accepted that a certain number of years, e.g. a number of reckoned years that have passed since Creation used in popular calendars, or that have had passed since the first ruler in the King list. But, there aren't enough names to fill that span of time, or there is some symbolic reason why there must be a certain number of generations in that span of time. So, the authors conclude that each of those rules must have been very long lived in the absence of evidence to the contrary in the tradition.
Of course, I reject the possibility that people really did live lives these longs as the literal reading would suggest.
There is no really decisive way at this point to distinguish these accounts, or to even know how the original intended audiences viewed them - as factual or a tall tales. But, it doesn't hurt to consider the possibilities and wonder if there will every be a way to test them.
Legendary history is better than nothing and archaeological finds have accurately been informed by them, but they must be used with caution.