Methuselah lived to be 969 years.
But after the flood, people did not live as long, only about 120 years. Then God shortened it to 70 years. Any older than 70 is considered a bonus.
Genesis 6:3
New International Version
3 Then the Lord said, “My Spirit will not contend with[a] humans forever, for they are mortal[b]; their days will be a hundred and twenty years.”
Psalm 90:10
New International Version
10
Our days may come to seventy years,
or eighty, if our strength endures;
yet the best of them are but trouble and sorrow,
for they quickly pass, and we fly away.
Some people think that the Earth's atmosphere changed after the flood and shortened the life span of humans, and perhaps animals as well.