You overlooked a fairly obvious error in your statement. The seed line which Christ would come through Noah was perfect down through the generations. Thus Noah's wife was also perfect also or else you shall be saying that Christ came from a corrupted bloodline through Mary.
Genesis 5
This is the book of the generations of Adam. In the day that God created man, in the likeness of God made he him;
2Male and female created he them; and blessed them, and called their name Adam, in the day when they were created.
3And Adam lived
an hundred and thirty years, and begat a son in his own likeness, and after his image; and called his name Seth:
4And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters:
5And all the days that Adam lived were nine hundred and thirty years: and he died.
6And Seth lived
an hundred and five years, and begat Enos:
7And Seth lived after he begat Enos eight hundred and seven years, and begat sons and daughters:
8And all the days of Seth were nine hundred and twelve years: and he died.
9And Enos lived
ninety years, and begat Cainan:
10And Enos lived after he begat Cainan eight hundred and fifteen years, and begat sons and daughters:
11And all the days of Enos were nine hundred and five years: and he died.
12And Cainan lived
seventy years and begat Mahalaleel:
13And Cainan lived after he begat Mahalaleel eight hundred and forty years, and begat sons and daughters:
14And all the days of Cainan were nine hundred and ten years: and he died.
15And Mahalaleel lived
sixty and five years, and begat Jared:
16And Mahalaleel lived after he begat Jared eight hundred and thirty years, and begat sons and daughters:
17And all the days of Mahalaleel were eight hundred ninety and five years: and he died.
18And Jared lived
an hundred sixty and two years, and he begat Enoch:
19And Jared lived after he begat Enoch eight hundred years, and begat sons and daughters:
20And all the days of Jared were nine hundred sixty and two years: and he died.
21And Enoch lived
sixty and five years, and begat Methuselah:
22And Enoch walked with God after he begat Methuselah three hundred years, and begat sons and daughters:
23And all the days of Enoch were three hundred sixty and five years:
24And Enoch walked with God: and he was not; for God took him.
25And Methuselah lived an
hundred eighty and seven years, and begat Lamech.
26And Methuselah lived after he begat Lamech seven hundred eighty and two years, and begat sons and daughters:
27And all the days of Methuselah were nine hundred sixty and nine years: and he died.
28And Lamech lived
an hundred eighty and two years, and begat a son:
29And he called his name Noah, saying, This same shall comfort us concerning our work and toil of our hands, because of the ground which the LORD hath cursed.
30And Lamech lived after he begat Noah five hundred ninety and five years, and begat sons and daughters:
31And all the days of Lamech were seven hundred seventy and seven years: and he died.
32And Noah
was five hundred years old: and Noah begat Shem, Ham, and Japheth.
Why so long? Why wait five hundred years; over 312 years more than anyone else in his generations?
Genesis 6:1-10
And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them,
2That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose.
3And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.
4There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
5And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
6And it repented the LORD that he had made man on the earth, and it grieved him at his heart.
7And the LORD said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them.
8But Noah found grace in the eyes of the LORD.
9These are the generations of Noah: Noah was a just man and perfect in his generations, and Noah walked with God.
10And Noah begat three sons, Shem, Ham, and Japheth
It took Noah longer than any in his generation before him because he could not find a suitable wife for himself. The verses mentions the sons of God, in which Adam was a son of God; but what of the women from his line? They also corrupted themselves with wordly men. Noah's wife was NOT purely of Adam and Eve's bloodline or else the scriptures would not have started with the generations of Noah. It would have continued in Adam's generations.
Look at verse 9 of Genesis 6. Noah was a just man. Of all the wickedness around him, he stayed righteous and as such had to find a woman who was receptive of his righteous way of living. He was perfect in his generations in that he was the last man
born of the union of a man and a woman of pure Adamic blood. He also walked with God. Amid all the wickedness and of the fact that he was unequally yoked with a woman not of pure Adamic blood, he continued to walk with God. Therefore he found grace in the eyes of the Lord.
Noah's wife was not perfect. Her blood was not pure.
Genesis 9:20-29
And Noah began to be an husbandman, and he planted a vineyard:
21And he drank of the wine, and was drunken;
and he was uncovered within his tent.
22And Ham, the father of Canaan, saw the nakedness of his father, and told his two brethren without.
23And Shem and Japheth took a garment, and laid it upon both their shoulders, and went backward, and covered the nakedness of their father; and their faces were backward, and they saw not their father's nakedness.
24And Noah awoke from his wine,
and knew what his younger son had done unto him.
25And he said, Cursed be Canaan; a servant of servants shall he be unto his brethren.
26And he said, Blessed be the LORD God of Shem; and Canaan shall be his servant.
27God shall enlarge Japheth, and he shall dwell in the tents of Shem; and Canaan shall be his servant.
28And Noah lived after the flood three hundred and fifty years. 29And all the days of Noah were nine hundred and fifty years: and he died.
How was Noah uncovered? Ham not only saw the nakedness of his father, but told his two brothers as if to brag about it. But why curse his son Canaan and not Ham? Before my father passed, I had to help him do certain things as he was unable to do them fully on his own. I saw him naked but does this mean that one of my kids should be cursed? Also, in all the previously mentioned before Noah, after their first born they continued to have sons and daughters before they died. Noah died ant 950 years old. That's some 400 years after his first 3 sons without so much as another son or daughter!
Jesus was not born of a union of a man and a woman. He was the only begotten of God, born of the Spirit. He was born in the likeness of a sinful body but the scriptures teaches that physically, life is in the blood. His blood did not come from a man and could not be tainted by the woman by protection of her placenta.