That is like asking if goldilocks was the only person who ever broke into the bear's house and slept in their beds
Noah was the only person on earth who lived a Godly life, and he communicated with God.
God spared (not speared) Noah and his family as they were the only people who still remembered/believed in him while the rest of the population of the earth had turned to wicked and deceitful ways. God almost destroyed the whole earth but because of Noah and his love for him God decided just to begin again with his family.
The children of Noah were descendants of Adam. Only Noah and his children survived, and so repopulated the earth.
At the time, the Solar System was believed to be fake. People believed only Earth was real.
Never! People only believed that.
That would mean they all descended from Noah.
Noah's Ark was made of wood. Wood naturally floats. It is believed to have been a barge shape and needed only to float. Check out Ron Wyatt. He thought he found the location of the ark in Turkey.
Noah was pretty much the only person of his time trying to obey the rules of God (besides his family). God trusted Noah (as well as some others in the near and distant future) to do his bidding without complaints.
For the length of time they were on the Ark, many prayers would have been offered for their safety. It is not doubt that much fasting was also done as the two are in accordance with giving thanks to God for their safety.
Noah was chosen because he was the most righteous man on earth.(Genesis 7:1)(Ezekiel 14:14)He 'walked faithfully with God' (Genesis 6:9NIV)He was a "preacher of righteousness"(2 Peter 2:5 NIV)He showed 'godly fear'(respect)and faith(Hebrews 11:7ASB)
Noah and his wife along with their three sons and their wives were protected in the ark but all others perished. The flood covered the tops of the highest mountains and every area of the earth shows evidence consistent with this.
The outer core has the most liquid out of any layer in the earth. It is about 95% lava.