Yes and no. There is more to take in account.
1. There is position / effect to check. You can roll a 6, but with a limited position, you can't inflict harm (maybe you can break their armor or magic defense).
2. If you make a Parry move, you are not making an Action Roll. And you resist the consequence of an Action Roll. So, if an enemy attacks you, you can try to avoid the attack by making an Action Roll (if in the fictional situation you can do, i.e. if you are tied up, you cannot flee), or you can try to parry the attack (and you can parry ONLY an attack, not any kind of danger). If you make an Action Roll, to avoid the enemy attack, you can push or keep the stamina for the (possible) Resistance Roll. If you try to parry, and you fail, you don't have any other option: you suffer harm (or the consequence of the attack).
3. Just to be clear, the NPCs can make their move first, if they have the opportunity or the power.