Minecraft steve should be able to become every class, why? Let me tell you.
Saber. Steve is a master of using the sword, using many different types and can use them no matter the form, with a strong sweeping edge attack. It's his strongest weapon
Archer. Master of the bow AND crossbow, he can preload arrows, shoot rockets, and shoot strong flaming arrows.
Lancer. Steve uses a strong trident which has the ability to use lightning, fly with it, and have it return to himself.
Caster. He has TERRITORY CREATION EX. Full manipulation of the world, bottles of enchanting, runes to enchant his armor and weapons to the next level, including his masters armor too. He also has potions that can increase his abilities, and he can create a workshop (beacon) that boosts his allies in a range.
Assassin. He has a full suit of redstone traps including explosives to his advantage, and can hide his prescence with potions or sneak.
Rider. He can ride horses donkeys and mules to a good ability, as well as pigs and striders, for sure his weakest class. (Includes minecarts and boats)
Berserker. The true strength of steve, punching trees with his bare hands, killing a dragon mother which didn't even bother him, the true rage of the twelve year old controlling him. Also axe = berserker now lmao
Lets not forget he can be avenger as well, in the form of Herobrine.
Creative mode as ruler as well.
Watcher class? Spectator mode.