The Flood and the destruction of Sodom, etc. PRECEEDED Christ’s Sacrifice.
What you are describing is the notion that the rules can somehow change AFTER His Sacrifice.
It was the same God wag.. Gods righteousness and the sin of man did not change from the OT to the NT
Gods Holiness is the same. The sin of man is the same.. The offense before God is the same
OT men were saved by grace, just as they are in the new..
So the OT examples are still valid
God judged infants by the same standard in the OT that He judges men and infants by in the NEW Testament.