Now you are just creating invisible hit points. It doesn't actually result in "not Superman" which was the stated goal.
Invisible hit points aren't necessarily bad. It depends on the exact design of the game.
My preference is to model something like Mythic Bastionland. In this game, you have your Vigor (which is also an ability score you have to roll under sometimes), your Armor, and your Guard. Your Armor is variable -- it depends on your armor, helmet, and shield. Your guard is your Armor + 1d6, which you roll when you make your character. In combat, damage goes to your Guard first (which replenishes outside of combat), and then to your Vigor. At half Vigor, you get a wound (not good), and at 0 Vigor you need to be saved in a round or else you die. All damage is reduced by your Armor before it gets applied to your Guard.
The reason I like this is because I really like damage reduction mechanics and I like the idea of essentially temp hit points a lot. I think leaning more on temp hit points that quickly replenishes during an adventure and having damage negation just flatout feels better for both parties. Now, in Mythic Bastionland, there is no to-hit roll; you roll damage and, if your damage beats the opponent's armor, the overfill goes against their Guard/Vigor. This makes combat very fast. You know immiedietly if you were able to hurt someone, and the Guard temp HP serves as a narrative tool to inform you of what the fictional world looks like afterward.
Technically, none of this is necessary. Hit points wrap all this into one. But, I often find myself feeling unsatisfied with hit points as they are in typical D&D. I think my favorite version of D&D hit points was in the otherwise ill-designed Dark Souls 5E RPG. In that game, you have your typical hit points (average), but when combat begins, you roll all your hit dice and gain that much temp HP. Temp HP + HP can be spent in increments of 1/2/3 to use special weapon maneuvers, and the temp HP comes back at the start of every combat. This represents a very cool idea in my mind where even though a warrior may be severely wounded, if they get ambushed, fighting spirit and adrenaline and desperation kick in, allowing them to fight on despite said wounds. It also lets you do some cool things with fleeing a combat and then setting up an ambush when chased. The enemy had you on the ropes, but in the last 10 minutes, you were able to gather yourself, and when combat starts again, your normal HP is low but that temp HP gives you a "shield" to potentially turn the tides with.
What these ideas have in common is that they manipulate BOTH the MECHANICS of hit points AND the fictional meaning of them in interesting ways. Now, anyone who is really comfortable with D&D as a game might be thinking, well, I don't need all that fancy stuff to do that, hit points works just fine for me! And that's fine. But in the same way that I don't need initiative to run fun and fair combat, I still use it because it lets me do interesting things in ways I find satisfying. Like Gygax said, the secret is that no rules are needed at all, but having these kinds of rules can change the feel of the game, and I find that very valuable.