My sole objective is to try to guess the motives of the Bible's writers
It's OK to guess and speculate.
..in the
Gospel of Mark the only mention by names of Jesus' family -- with an important exception -- is this well-known passage:
Mark 6:3-4 said:
Is not this the carpenter, the son of Mary, the brother of James, and Joses, and of Juda, and Simon? and are not his sisters here with us? And they were offended at him But Jesus said unto them, A prophet is not without honour, but in his own country, and among his own kin, and in his own house.
That's it!!
You're forgetting Mark 1:1 where Jesus' Father is named.
The minimal mention of family names throughout Mark can be plausibly explained by a presumption that readers only needed to be told once, and/or that by the time of writing this was already sufficiently common knowledge. (Other Gospels. Oral transmission.)
Father Joseph is mentioned ZERO times in the entire Gospel. Brother James -- who became a top pillar of the Church before the Gospels were written -- is mentioned ONLY here in all the Gospels. (Matthew and Luke offer the same list of brothers; Matthew replaces "the carpenter" with "the carpenter's son," still not naming Jesus' father except in the Nativity...
Who is the central figure in the Gospel?
Not Joseph. Not James.
Who were the people who accompanied Jesus during His ministry? The people who were there.
Mark 9:2 Mark 10:35 Mark 3:16
There's names all over the place in Mark.
I wrote that there is an important exception; a place where
Mark does repeat his mention of Mary and two of Jesus' brothers.
Mark 15-16 said:
[15:40] There were also women looking on from a distance. Among them were Mary Magdalene, Mary the mother of the younger James and of Joses, and Salome. These women had followed him when he was in Galilee and ministered to him ...
. . .
[15:47] Mary Magdalene and Mary the mother of Joses [Joseph] saw where Jesus' body was laid.
. . .
[16:1] And when the Sabbath passed, Mary Magdalene, and Mary the mother of James, and Salome, bought spices, so that they might come and anoint Him.
The "other Mary" is the mother of James and Joses, and therefore also the mother of their older brother Jesus! But does it seem odd not to just call her "Jesus' mother"?
No. Why is that odd? Whose mother would she otherwise be if not Jesus' mother.
John 19:25 names her as Jesus' mother.
Why this criteria of "oddness" that a writer would take for granted that readers knew Jesus mother Mary would be at Golgotha?
For some reason the author of Mark is reluctant to say this out loud! Why?
I think it's a stretch to suggest reluctance.
You ask why would he be reluctant.
And I say
there's no reason why, therefore we are allowed to rule out reluctance.
(Matthew and Luke have the same reticence, with the former changing two instances of that Mary to just "the other Mary." John refers to Jesus' mother, e.g. in his famous last words, but mentions her by name . . . ZERO times.
Mary the mother of Jesus is the one Mary whose name
doesn't need disambiguation. It's the other Marys whose names need clarification.
This reluctance to identify Mary as Jesus' mother strikes me as peculiar -- and should seem peculiar whether you treat the Gospels as fact or fiction.
Argumentum ad peculiarum?
Speculation is fine. But arguing from incredulity won't persuade folks who think yours is the odd exegesis of the text.
Does the reluctance to name Mary, Joseph and Jesus' brother James seem peculiar?)
Not to me.
This James is called "the First Bishop of Jerusalem", and was assassinated in the 60's AD, BEFORE the alleged writings of the Gospels.
Again. Not one of the disciples travelling with Jesus throughout the Gospel of Mark.
By your own reasoning it would be "peculiar" if someone who came later was conspicuously elevated into prominence in an account of events which took place before he was bishop of Jerusalem
There are other oddnesses in Gospel names which I'll mention in a follow-up post.