We currently have Steve at Wall level primarily for breaking stone blocks in a short timeframe. Issue with this though, is that Minecraft treats this as them being able to compress a cubic meter block(s) into their inventory so long as the block follows those rules.

To add on, in the novel Minecraft: The Island, the protagonist can't damage stone without hurting their own hands, and it takes them a long time to even damage it significantly.

Honestly, this should straight up debunk anything wall level in the games, and given how arrows from a regular crossbow can instantly kill them, I'm inclined to just make them 10-A.

Okay, so anyone who's played Hardcore Minecraft knows how mere creeper explosions one-shot you even with end-game armor.

Or even worse when even with the right enchantments on your best armor, you can die to fall damage/kinetic energy.

So either 9-B or 9-C.

Lifting Strength

So because of how lifting blocks work, Class K needs to go, and the only thing usable for lifting strength is Steve wearing a full set of golden armor. I think that's gonna be Class 25 or something.