Surgoshan said:The primary definition of cover is "The target is around a corner or protected by terrain". One of your allies is not terrain, a wall, nor a corner for you to be around. The bit where allies provide cover only comes up under Creatures and Cover. "When you make a ranged attack against an enemy and other enemies are in the way, your target has cover". Bolding mine. Your allies only count as cover for a ranged attack.
So, no, your allies do not provide sufficient cover for you to hide from an enemy.
I read the definition as allies to not provide cover to an enemy target, but do provide cover for you against an enemy target.Surgoshan said:"When you make a ranged attack against an enemy and other enemies are in the way, your target has cover". Bolding mine. Your allies only count as cover for a ranged attack.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.