This is just wishful propaganda. Mark was not the first, it looks as though some of the gnostic writings were. And as for 70ce thats laughable. There was a early writer (cant think of his name) and critic who wrote about many of the Christian and gnostic writings he lived from 100-165 ce and he never even mentions any of the gospels.
Biblical scholar claims to have found the oldest known Gospel — inside a mummy mask
by opusdei1972 10 Replies latest watchtower bible