It is not really a matter of the game being "RPG", many modern shooters have leveled gear, while older RPGs also exist without such feature. Anyway, enemies are definitely leveled, similarly to The Witcher 3, this can be seen in the gameplay demo. And items have rarity levels at least, since the demo also shows for example a purple "epic" weapon. It is not clear however how much difference there is between the tiers, it could be just +20% damage going from the most common variant to the legendary one, or any other number.