Shem was the ancestor of all the sons of Eber.
Eber is where the word Hebrew comes from. Moses is making a connection for the children of Israel, showing God's divine hand and direction in their lineage even before they existed. They are the sons of Eber, His chosen people.
When we come to God we have a new sense of protection and leading from God. But when we reflect on how we came to Salvation we soon see God's involvement in our lives before we knew Him.
We see where God was calling us.
We see how he used the good and painful experiences in our life to draw us to HIm.
We identify the people used of Him as a light along our path to salvation.
We see choices that God used to lead us on - because, before we loved Him, He first loved us.
We can give thanks for all He has done even before we knew Him.