As far as huge ages described in ancient literature goes- for the ancients, numbers had mystical, symbolic and religious significance as well as just being numbers. We still have a few traces of these beliefs, such as lucky 7 and unlucky 13.
Ancient numbers of any sort were not necessarily intended to be taken literally by their audiences. Some of them had other meanings- meanings that are now lost.
The ages in the kings lists, and the extremely old life spans of patriarchs in Genesis were likely in this same tradition.
The ages of the patriarch in the Bible have unusual patterns in the numbers that are unlikely to be random, as real ages would be.
As an example, if I remember correctly, Joseph in the bible (of the Egyptian famine fame) is recorded as living to be 110. While not impossible to attain, the Egyptians considered 110 to be a lucky number... leading to the question of if we should consider this age to be literal or mystically significant.
The Bible is full of weird numerology like this. Weird to us, that is, since we no longer understand the original meanings.