I'm pinging you to the post above in answer to your question. Noah wasn't saved by anything HE did. The scriptures clearly says "Noah found favor in the eyes of the LORD". It's clearly not anything Noah did to earn the Lord's favor otherwise we would have to conclude Noah earned his salvation which he did not. Why Noah found favor in the eyes of the Lord is not defined in scripture but it is clear the Lord had mercy and grace to Noah.
Noah found grace in the eyes of God because God foresaw Noah's faith (Heb.11:7).
The same reason that Abraham did.
For I know him, that he will command his children and his household after him, and they shall keep the way of the Lord, to do justice and judgement that the Lord may bring upon Abraham that which he hath spoken of him. (Gen.18:19)
Noah and Abraham found grace because God forsaw that they would have faith.
The same reason anyone finds grace, they do not reject it when it is offered.
That is what Noah's generation did.
The suggestion is that there was something different about Noah. Why say that?
1 Peter 3:18-20 18 For Christ R177 also died for sins once R178 for all, the just for the unjust, so that He might bring R179 us to God, having been put to death in R180 the flesh, but made alive in R181 the spirit; F62 19 in which F63 also He went and made proclamation to the spirits now in prison, 20 who once were disobedient, when the patience R182 of God kept R183 waiting in the days of Noah, during the construction of the R184 ark, in which a few, that is, eight R185 persons, R186 were brought safely through the water. F642 Peter 2:3-6 3 and in their greed R69 they will exploit R70 you with false R71 words; their R72 judgment from long ago is not idle, and their destruction is not asleep. 4 For if R73 God did not spare angels when they sinned, but cast them into hell and committed R74 them to pits of darkness, reserved for judgment; 5 and did not spare the R75 ancient world, but preserved Noah, R76 a preacher F12 of righteousness, with seven others, when He brought a flood R77 upon the world of the ungodly; 6 and if He condemned R78 the cities of Sodom and Gomorrah to destruction by reducing them to ashes, having made them an example R79 to those who would live R80 ungodly lives thereafter;
Something separated Noah so that he found grace in the eyes of the Lord. Are there any hints above as to what it might have been?
I say this because I simply do not believe that God acts arbitrarily.