In the days of Noah people constantly thought and did that which was wicked in the sight of the Lord. "5 Then the Lord saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually." (Genesis 6:5). God judged the world and destroyed everyone who was not on the Ark. Only Noah and his family were spared God's wrath on sinners.
"Just as Noah and his family had to go through a door to be saved, so we must go through a door (i.e., the Lord Jesus) to be saved. Jesus is the only Ark of Salvation for us to receive eternal life with our Creator."
Read more: "The Ark is a Picture of Salvation" http://onewayjesus.weebly.com/blog/the-ark-is-a-picture-of-salvation
Also see: I Am the Door (John 10:1–10) - John MacArthur https://youtu.be/ANvoTfDSZgc