I was sort of taking it as read that such details as who killed Goliath (if the story is based in fact) were probably made up.
Probably the numbers were made up; the battle was probably genuine; the two tribal factions were battling in what was essentially a power vacume; the small tribal territories had allied themselves with either the Egyptians, Hittites or Mitanni as the main superpowers in the area.
The former two were in turmoil - the latter, the Hittites, in terminal decline, and Mitanni was being absorbed by the nascent Assyrian kingdom.
Land was up for grabs, and there was no 'peacekeeping' power to quell the strife.
The various skirmishes mentioned in Judges, 1 & 2 Samuel, whilst being exaggerated, bear witness to the mess in the area at that time (1200-950 BC)