There is a well-known contemporary source that 70 was considered old age, but not miraculous. Psalm 90:10, KJV.
The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away.
[Yes, I realize the irony of citing the Bible here, but it's not a likely place to exaggerate life expectancy of ordinary folk.]