Alleged Contradictions in the Qur'an answer

The Fate of Noah's Family
What about Noah's son? According to Sura 21:76, Noah and his family is saved from the flood, and Sura 37:77 confirms that his seed survived. But Sura 11:42-43 reports that Noah's son drowns
Verses in question:

21:76 (Remember) Noah, when he cried (to Us) aforetime: We listened to his (prayer) and delivered him and his family from great distress.

37:77 And We made his progeny to endure (on this earth)

11:42-43. So it (the ship) sailed with them amidst the waves like mountains, and Noah called out to his son, who had separated himself (apart), "O my son! Embark with us and be not with the disbelievers."
The son replied: "I will betake myself to a mountain, it will save me from the water." Noah said: "This day there is no saviour from the Decree of Allâh except him on whom He has mercy." And a wave came in between them, so he (the son) was among the drowned.

1. With regards to verse 21:76 which states that the family of Prophet Noah (peace be upon him) was saved, the Qur'an itself clarifies what it means by his "family", for Prophet Noah himself, asked God about this:
11:45-47. And Noah called upon his Lord and said, "O my Lord! Verily, my son is of my family! And certainly, Your Promise is true, and You are the Most Just of the judges."
He said: "O Noah! Surely, he is not of your family; verily, his work is unrighteous, so ask not of Me that of which you have no knowledge! I admonish you, lest you be one of the ignorants."
Noah said: "O my Lord! I seek refuge with You from asking You that of which I have no knowledge. And unless You forgive me and have Mercy on me, I would indeed be one of the losers."
Thus, here Allah distinguishes between our blood family and our true family in faith. As the Qur'an states about our family:
49:10 All believers are but brethren.
Thus, there is no conflict between verses 11:42-43 and 21:76. With regards to verse 37:77, it simply states that his progeny endured and according to some narrations, it will until the end of humanity. There are some who have interpreted verse 37:77 to imply that his followers did not have any surviving descendants (see Ibn Kathir, Stories of the Prophets, Maktaba Darussalam 2003, p.88). However, others disagree as Shaykh Abdul Wahhab At-Turayri mentions:
With respect to the verse: “And We made his descendants those who remained.” [Sûrah al-Sâffât: 77], we cannot derive such a conclusion, since the wording in the verse is not specifically exclusive. There is no contrary indication that we need to deduce. Noah’s descendants were definitely “those who remained”; however that is understood in the context of comparison with the unbelievers who stayed behind. As for the possibility of other passengers being on the ark and the possibility of their leaving descendants, it is a possibility that is not ruled out by the verse. It is a matter that is not clearly addressed, and therefore one about which we should not speculate.

The Qur’ân simply does not state how many people went with Noah, nor does it say anything about what other people besides Noah’s people may have been living on the Earth at the time.

The Qur’ân does not discuss the extent of the flood. Scholars of Qur’anic commentary differ on the matter. For instance, Ibn `Atiyyah and al-Alûsî are among the commentators who favor the idea that the flood was a regional phenomenon. All the direct statements about the global scope and extent of the flood come from various unverifiable accounts taken from Jewish and Christian sources. Since we only know about matters of the unseen through revelation in the Qur’ân and authentic Sunnah, this question cannot be answered decisively.

...With respect to the verse: “And We made his descendants those who remained.” [Sûrah al-Sâffât: 77]

On the basis of this verse, some scholars have claimed that no other human beings were left on the Earth. It is related from Qatâdah that he said: “Humanity, all of them, are from the descendants of Noah.” [Tafsîr Ibn Kathîr (5/347)]

However, this verse is making no such claim, since no reference is made to humanity as a whole or to the world as a whole. Therefore, the most that we can take from the verse with certainty is that Noah’s descendants survived while the unbelievers from among his people did not.

As for the hadîth attributed to the Prophet (peace be upon him) about the three sons of Noah (peace be upon him), they are weak and cannot be used as evidence.
Based on the above points, we can understand that the verses do not contradict since Noah's son was not considered amongst Noah's true family, and verse 37:77 does not include Noah's son nor does it exclude Noah's followers.

2. Another point to note is the broad range of meanings associated with the arabic words Ahl (family) and dhuriya (progeny) used in these verses. One frequently hears the Islamic terms Ahlus-Sunnah (People/followers of the Sunnah), Ahlul-Hadeeth (People/followers of hadeeth) and Ahlul-Kitaab (People of the Book i.e. Christians and Jews). And in the Qur'an it says:
27:34 She said: "Kings, when they enter a country, despoil it, and make the noblest of its Ahl its lowest thus do they behave.

28:4 Truly Pharaoh elated himself in the land and broke up its Ahl into sections

28:15 And he entered the city at a time when its Ahl were not watching
In the above verses, all commentators and translators have interpreted Ahl to mean the people/inhabitants of the city, not the 'family' of the city. And the word Ahl has also been interpreted as people in the following verse describing Prophet Ishmael (Ismaa'il):
19:55 He enjoined upon his Ahl (people) worship and alms giving, and was acceptable in the sight of his Lord.
Just as Ahl is a broad term, so is dhuriyya, as the Qur'an says:
36:41 And a Sign for them is that We bore their dhuriya [through the Flood] in the loaded Ark
In the above verse, Yusuf Ali has even chosen to translate dhuriya as 'race' and Muhammad Asad makes the following comment:
The term “offspring” denotes here the human race as a whole (cf. the recurring expression “children of Adam”). (Asad, The Message of the Qur'an, The Book Foundation 2003)
Thus, when we re-read the passages with these meanings in mind, we find that verses 21:76 and 37:77 are statements concerning the survival of his followers and supporters, therefore it does not contradict verses 11:42-43 which speak about the fate of Noah's son.

3. Critics also point out that Noah is commanded to take all his family and the believers on board the ark with him, but not those people "against whom a word has already been passed" (verse 11:40). Critics feel that this phrase implies that Noah was instructed not to take certain people on board the ark, yet he disobeyed when he called his son to join him on the ark. This claim is based on an incorrect understanding of the mentioned phrase. The usage of 'word' in the phrase implies the decree of Allah swt, hence Noah may simply have been instructed to leave the disbelievers behind - those who were decreed to stay behind. The verse does not necessitate that Noah was informed who specifically was doomed and who was not.