And so, the author of G-Mark adjusted the account to express sentiment and a kind of spiritual message? Is that correct?
I rather think you're looking at it the wrong way.
Mark is writing an account of how Jesus fulfils the prophecies made to Israel (Mark 1:1-3). The author takes elements from oral and liturgical tradition, and orders them in such a manner as to convey that message. He calls it a 'gospel' – the Greek is
euangelion, meaning 'good news' or 'glad tidings'. In a Christian context the term was understood as the preaching of Jesus Christ as having suffered death to procure salvation and thus the coming of the kingdom of God.
Like the other gospel writers, he orders the elements of Jesus' history into a narrative. Does he write them in the order in which they occurred? Maybe, maybe not – that's not his purpose.
But here the point is that Mark uses OT prophecy to support his gospel, here as elsewhere (he opens with Isaiah). The use of Psalm 22, not just Jesus' cry, but the dividing of his garments (v18-19) it is used to highlight Jesus' suffering, and our suffering, but in the end it is triumphant. So the inclusion is a pointer – 'read the Psalm and that will educate you in regard to what is happening here'.
This thread is titled 'Was the Gospel of Mark adjusted by Christians?'. Do you suggest that it was....adjusted?
AFAIK the only points of contention is the 'Son of God' in the first verse, and Chapter 16, verse 9 on, which are missing from some early manuscripts, but that is well known, well attested, and inconclusive. So if you want to call that 'adjustment', then OK, but then the point is, what's your point, we all know that?
If you want to make the point that
all or more of it has been adjusted, then that's an uphill climb.