3. Is it a certainty that Noah and his clan and the animals n his area were the only living beings on the planet?
Off course the flood was GLOBAL according to Quran and not a single human being left alive except those on the ship.
Read it at Islamqa:
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https://islamqa.info/en/answers/130...t-flood-at-the-time-of-nooh-peace-be-upon-him
The clear text of the Qur’an indicates that everyone who was on earth drowned in the flood, and no humans or animals were saved except those whom Nooh took with him on board the ark.
Allah, may He be exalted, said (interpretation of the meaning):
“And We saved him and those with him in the laden ship.
Then We drowned the rest (disbelievers) thereafter”
[ash-Shu‘ara’ 26:119-120].
“(So it was) till then there came Our Command and the oven gushed forth (water like fountains from the earth). We said: ‘Embark therein, of each kind two (male and female), and your family, except him against whom the Word has already gone forth, and those who believe. And none believed with him, except a few.’”
[Hood 11:40].
“They denied him, but We delivered him, and those with him in the ship, and We made them generations replacing one after another, while We drowned those who belied Our Ayat (proofs, evidences, lessons, signs, revelations, etc.). Then see what was the end of those who were warned”
[Yoonus 10:73].
The Qur’anic text also indicates that the earth was only populated after that by the descendants of Nooh (peace be upon him). As for the believers who were saved with him in the ark, none of their descendants were left. So all the people on earth now are descended from Nooh (peace be upon him).
Allah, may He be exalted, says (interpretation of the meaning):
“And indeed Nooh (Noah) invoked Us, and We are the Best of those who answer (the request).
And We rescued him and his family from the great distress (i.e. drowning),
And, his progeny, them We made the survivors (i.e. Shem, Ham and Japheth).
And left for him (a goodly remembrance) among generations to come in later times.
Salamun (peace) be upon Nooh (Noah) (from Us) among the Alameen (mankind, jinns and all that exists)!"
Verily, thus We reward the Muhsinoon (good-doers)
Verily, he (Nooh (Noah) ) was one of Our believing slaves.
Then We drowned the other (disbelievers and polytheists, etc.)”
[as-Saaffaat 37:75-82].
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Therefore, question remains how Noah was able to make such a huge Navel Ship with the help of stone tools?
According to Quran, all the animals in pairs were able to board the ship.
Are you able to imagine how much Water and Grass and Meat the animals need if they have to stay in the ship for couple of months?