Verses in question:
Genesis 6:3: “Then the LORD said, “My Spirit shall not abide in man forever, for he is flesh: his days shall be 120 years,”
Psalm 90:10: “The years of our life are seventy, or even by reason of strength eighty; yet their span is but toil and trouble; they are soon gone, and we fly away.”
Does this this indicate that God is limiting each human’s lifespan to 120 years? Is that in contradiction to Psalm 90:10?
A simple reading of the passage in the narrative in which it is found (which explicitly states that people after the flood lived much longer than 120 years in Genesis 11) reveals that this is not the case. This is found in the Noahic cycle of the book of Gensis and is not a prediction of the life span of humans in general, but of the time span before the flood in particular. Notice that this statement is explicitly followed by God’s comment, “I will blot out man whom I have created from the face of the land…” (6:7). The very passage itself militates against the reading that this is a prediction of the lifespan limit for all human life but is rather a pronouncement of the judgment that was about to befall the sinful humanity of Noah’s day. Since Genesis 6:3 does not teach that there is a life span cap, there is no contradiction between this and the verse in Psalm 90.