Could humans other than Noah and his family have been on the ark and preserved through the Great Flood. Some believe that Cain’s line was preserved and many of his descendants live in our modern world today. They base this on Genesis 6:19 where Noah was commanded to bring two of all flesh into the ark. Could this not imply that other humans were brought aboard the Ark along with Noah and his family?
I think that interpretation goes beyond the Bible’s intent. The only humans mentioned as either getting on or off the Ark are Noah and his family. From Genesis 10 we can reasonably conclude that everyone alive today is a descendant of either Ham, Shem, or Japeth. Descendants of Cain are not necessary to complete the table of nations, nor are they mentioned as part the post flood world. The Hebrew word for flesh applies to both humans and animals and is normally interpreted as referring to Noah, his family, and at least 2 of every animal specie.