The Cleric has a d8 hit die and the ready-made hero starts with 16 Wisdom. Cure Wounds restores 1d8 hit points to the caster, which lets a Cleric stay in a fight longer than anyone expects.
Play a ClericCast Cure Wounds before you are in danger, as each cast uses a spell slot.
Take a long rest when slots run out.
High Wisdom makes you good at noticing what others miss.
The Acolyte background adds Wisdom and training in Insight.
The Tough feat makes you even harder to bring down.
Cure Wounds currently heals the caster. Potions can be used by every hero.