These are the records of the generations of Noah. Noah was a righteous man (אִ֥ישׁ צַדִּ֛יק; LXX: ἄνθρωπος δίκαιος), blameless in his time; Noah walked with God. (Gen 6:9, NASB)
Commenting on the nature of Noah’s righteousness in Gen 6:9, one Protestant scholar wrote the following, showing that the author of Genesis is not teaching alien imputed righteousness for Noah (as well as Enoch in Gen 5:22, 24):
The other component of Yahweh’s call to Abraham is to ‘walk before me’ (hithallēk lĕpānay). Hlk occurs in the OT over 1,500 times. Most commonly it refers to walking in a non-metaphorical sense; but it also occurs hundreds of times as a metaphor for life, and particularly, a life lived in either obedience or disobedience.
Like tāmîm, references to ‘walking with’ Yahweh are found prior to Genesis 17. In Genesis 5:22 and 24 we are given a glimpse of Enoch who ‘walked with God [wayyitallēk ḥănȏk ‘et-hā ĕlōhîm]’ (Gen. 5:24, my tr.; cf. 5:22). The description of Enoch walking with God is clearly significant since he alone in a long list of people is not said to die; instead, he simply ‘was not’ because ‘God took him’. Similarly, we are told that ‘Noah was a righteous man; blameless in all his ways. Noah walked with God [‘et-hā ĕlōhîm hithallek-nōaḥ]’ (Gen. 6:9, my tr.) This description of Noah’s character is also significant since it is on account of his righteousness that Yahweh saves him through the ark (Gen. 7:1). (Karl Deenick, Righteous by Promise: A biblical theology of circumcision [New Studies in Biblical Theology 45; London: Apollos, 2018], 32, emphasis in bold added)