Tom is the oldest in that he’s Tolkien’s oldest fictional creation. Tolkien made him up one day for his children’s bed time story. In this context, it explains

Tom is the oldest in that he’s Tolkien’s oldest fictional creation. Tolkien made him up one day for his children’s bed time story. In this context, it explains why Tom feels so off from Middle Earth. Personally, I like the character and I’m surprised to hear that a lot of people didn’t like him.