"the case of Noah was all about showing faith"
God could have tested Noah's faith in other more useful ways than having him labor on an inadequate means of saving that God still had to step in and apply supernatural patches to. I can think of a lot more efficient ways for an allpowerful God to kill off all but a few than having to drown the whole planet with water killing off, not only wicked people, but millions of innocent animals.
Why does he have to resort to killing the wicked by the use of traumatic events like floods, wars and armageddon? Why doesn't he just have all the wicked die in their sleep? Because contrary to what JWs and many others teach, the God of the bible is a vengeful sadist who takes pleasure in making the wicked suffer a horrendous death:
"And I will cause distress to mankind, and they will certainly walk like blind men; because it is against Jehovah that they have sinned. And their blood will actually be poured out like dust, and their bowels like the dung." - Zephanaiah 1:17, oNWT
Modern western civilization is more refined morally than he is. Today those who are put to death by the state face lethal injection instead of the kinds of barbaric carnage that the God of the bible seems to delight in.