Adam: 930 years
Seth: 912 years
Enos: 905 years
Cainan: 910 years
Mahalaleel: 895years
Jared: 962years
Methuselah: 969years
Lamech: 777years
Noah: 950years
(During this time the sin nature that some people think gradually limits years must have taken a break)
God makes the statement in Genesis 6:3 that He will limit mans years to no more than 120. Noah took his sons and daughters and their sons and daughters into the ark. How many generations is unstated but at some point God's statement must start coming into force:
Terah: 205years
Sarah: 127years
Abraham: 175years
Ishmael: 137years
Isaac: 160years
Joseph: 110years
Aaron: 123years
Moses: 120years
Joshua: 110years
Taken from search of "years" and "died" :
https://www.blueletterbible.org/search/search.cfm?Criteria=years+died&t=KJV#s=s_primary_0_1
Maybe I missed some my search terms didn't hit, but there are a few things clear:
1) No statement at all linking "sinful nature" to decline in years.
2) Big drop in ages lived after the flood. Nothing "gradual" about it. If there are deaths I missed that are gradually lower, they are only for this period.
3) And most important the "sinful nature" that we are supposed to have inherited from Adam and Eve should still be in it's stated operation today, limiting man's life years more and more if the theory is true.
Does anyone wish to redefine gradual now so they can support their fantasy theories? Lol.