These kind of questions are difficult to answer for a denomination that doesn't believe that what God tells us in Scripture is true. The ELCA casts doubt on Jesus being birthed by a virgin, that Jesus actually said what He is recorded to have said in the Bible, that hell or the devil are real or that God created everything in six days – all which is well-documented on this website. The ELCA even casts doubt or denies that Adam and Eve were actual real humans beings.
So the answer to the question, “How do you explain the very old ages of some of the people in the Bible (Old Testament)?” by ELCA pastor, Rosanne Swanson, is not a surprise. She writes,
“There are many theories about the ages recorded in the Old Testament — like years back then were not the same as years now so that there was a different counting system for years. Or, before the flood, people lived longer and after the flood they didn’t...” (read here)
How ridiculous that the ELCA even suggests that years may not have been the same as they are now.
Early church father and Christian theologian Augustine believed the genealogies written in Genesis to be literal chronologies. He believed what the Bible said, that pre-flood patriarchs lived to be around 900 years. (see Augustine, The City of God, Book 15, Chapters 11–12, pp. 436–440.)
Read just a few verses of Scripture on what God says about the age of people before the flood:
When Adam had lived 130 years, he had a son in his own likeness, in his own image; and he named him Seth. After Seth was born, Adam lived 800 years and had other sons and daughters. Altogether, Adam lived a total of 930 years, and then he died.
When Seth had lived 105 years, he became the father of Enosh. After he became the father of Enosh, Seth lived 807 years and had other sons and daughters. Altogether, Seth lived a total of 912 years, and then he died.
When Enosh had lived 90 years, he became the father of Kenan. After he became the father of Kenan, Enosh lived 815 years and had other sons and daughters. Altogether, Enosh lived a total of 905 years, and then he died (Genesis 5:3-11).
ELCA leadership: God is wiser, bigger, more powerful, more intelligent than you are. Stop telling His children that God's Word is full of myths and can not be trusted. You are pushing people away from God, and He will hold you accountable for your actions and your misleadings.