First, I'm not certain where all of these men lived, so it's difficult to tell how much interaction they would have had with each other. This being said, they are family, and since it is so clearly recorded in Scripture that this was the lineage to carry on God's promise to Eve in Genesis 3:15, I don't believe it's a non sequitur or illogical stretch of the imagination to assume that these men knew each other and talked to each other - a lot!
Second, at my house, we seek to read Scripture daily, and remind ourselves of God's promises to us through Christ. If Adam did this, think of how many days, and years he had to tell the story of the creation, fall, and hope for redemption again and again to his children, grandchildren, great-grandchildren, and on down the line. He lived 930 years! That's 339,450 days! God's work in history, and God's word spoken to be repeated again, and again, and again. Also, Adam and Eve had other children. The story of God in creation, and the fall, was repeated again and again.
Third, the number of years these people lived gives an incredible amount of validity and trustworthiness to the words of Scripture. Over time, there would have been more and more people who could challenge the story if folks were trying to add false details to it. Over time, Adam, Seth, Enosh, etc., would have been able to correct errors that people had about the story. Consider this, Adam died only 126 years before Noah was born, and Seth died only 14 years before Noah was born. Lastly, Adam's grandson, Enosh, was alive 84 years into Noah's life. Wow! I'm looking forward to seeing if there's more overlap in the lives to come.