The Warrior has the largest hit die in the game, a d10. The ready-made hero starts with 16 Strength and 16 Constitution, which makes this the most forgiving class for new players.
Play a WarriorStand in front and take the hits your allies cannot.
Melee cannot reach far enemies, so spend a turn closing in on archers and casters.
The Soldier background adds Strength and training in Athletics.
The Tough feat adds 2 maximum hit points at every level.
Yes. High hit points give you room for mistakes when nobody can heal you.