God limits human lifespan to 120 years

God Limits Lifespan to 120 Years.

When God's control of individual lifespan didn't kick in for centuries. 

Before the big flood, the Bible said--

Genesis 6:3 So the LORD said, My Spirit won't remain with human beings forever, because they're truly mortal. Their lifespan will be 120 years.

But after the big flood, the age of Abraham's father, Terah, was--

Genesis 11:32 Terah lived 205 years, and he died in Harran.

And the age of Abraham himself was--

Genesis 25:7 Abraham lived a hundred and seventy-five years. 8 Then Abraham breathed his last and died at a good old age, an old man and full of years.

And that of Isaac, a son of Abraham, was--

Genesis 28:35 Isaac lived a hundred and eighty years. 29 Then he breathed his last and died and was gathered to his people, old and full of years. And his sons Esau and Jacob buried him.

And that of Jacob, the son of Isaac, was--

Genesis 47:28 Jacob lived in Egypt seventeen years, and the years of his life were a hundred and forty-seven.

And the age of Levi, the son of Jacob, was--

Exodus 6:16 These were the names of the sons of Levi according to their records: Gershon, Kohath and Merari. Levi lived 137 years.

And the age of Moses was--

Deuteronomy 34:7 Moses was a hundred and twenty years old when he died, yet his eyes were not weak nor his strength gone.

And the age of Jehoiada, being a priest centuries after Moses, was--

2 Chronicles 24:15 But Jehoiada waxed old, and was full of days when he died; an hundred and thirty years old was he when he died.

Thus, before the flood, God placed a 120-year limit on the individual lifespan. But after the flood, many centuries went by before it took effect. Whew!

Some apologetics explain that Genesis announced, instead, that God would let 120 years pass before destroying the earth with a big flood. That is, while Noah built the ark, God waited 120 years before sending the flood; God had patience. The New Testament says--  

1 Peter 3:19 After being made alive, [Jesus] went and made proclamation to the imprisoned spirits-- 20 to those who were disobedient long ago when God waited patiently in the days of Noah while the ark was being built. In it only a few people, eight in all, were saved through water.

But--or so I assume--while Noah made the ark, God looked at the future world and saw that it hadn't changed; it was still bad. So what was the percentage in waiting patiently?