First gospel or not, Mark is surely the only New Testament book which calls itself a gospel. "The beginning of the gospel of Jesus Christ, the Son of God" is the title of this work, and its self-designation ought to shape any interpretation which respects the text.
"Gospel" can signify a literary genre, or a particular theological message, or a canonical writing normative in the life of the church. The Gospel of Mark is all three: a collection of traditions about Jesus presented in story form, a narrative constituting good news about God and his kingdom, and a writing which occupies a place of fundamental importance in the Scriptures of the church.
