I would, were I you, look at archaeological discoveries made in Palestine in 1993. I don’t think you’re as familiar with this as you make yourself out to be.
To be fair, though, that’s the “conventional wisdom” from the non-Judeo-Christian side of things, these days. So, if the OP heard or was taught that this is true, then it’s not surprising he treats it as a presumptive fact.
Seems like “King” David was a bit player in history and not really important.
From the perspective of a secular and merely geopolitical view, I’ll grant you that. Even
if David is who the Bible says he is – from the standpoint of his importance to the world – he’s still unknown outside the Levant of his day, from a political standpoint.
And yet, his importance – in terms of the spirituality of a large percentage of humans who live or have lived in the past – is
huge!
Heck, if you treat Jesus merely from the standpoint of politics, He’s just a leader of minor religious sect of a relatively powerless religious community in a backwater province of the Roman Empire. Big deal, eh? Yet… from the perspective of the impact – immediately and up through the present day – of His ministry and passion / death / resurrection?
HUGE!
So, I think I would counter that King David is massively important – and sets the stage for the even
more massively important ‘Son of David’ – in ways that transcend a merely geopolitical analysis.