one of the ravager's mechanics revolves around the shield blocking all the damage from the ravager.

It's not a ravager's mechanic, it's a shield mechanic. Shield used to block 100% of damages, but I added a feature that allows you to put a maximum damage absorption amount for shield (5 by default). If you don't like it, you can deactivate this specific feature in the configs ;)

Maybe have a config for specific mobs to have the shield absorb all the damage like how it's set with creepers. (Also I would consider it a mechanic of the ravager with the shield In mind because the ravager was released long after the shield.)