I don't think you really understand the kinetic force of modern weapons.
I have plenty of idea of what military equipment can do. How do you think I even know what a Maverick missile is? You say 20 mm, which can not penetrate a modern battle tank should leave bruises. That dude aint saving the world from aliens or supervillians unless they are a smaller threat than a mechanized Marine Battalion.
Comics have no idea either, which is why it's dumb to think superman would dodge a chunk of rock thrown at him or get buried under a brick wall falling on him, or us a piece of rebar to strike when its just a limp noodle in his hands.
Comic writers typically have no idea how physics work are massively inconsistent if for no other reason than there are so many of them doing the same character across different books and stories. I would expect more consistency in a single film of or series of them.
At the power level you describe he us literally living in a world of shadows and tissue paper, only the molten core of the planet is a tangible object to him.
Hence the living in a "world of cardboard". Watch the end of Man of Steel, Kal-El and Zod move through the world
almost as though it is not even there. Hitting Kal with an I-Beam only did something because using heat vision had already disoriented him. Cavill Superman is nothing in terms of power compared to his comic versions or even Reeve/Routh Superman. I think there are things our world that could effect him. Even 30 mm from an A-10 knocked him off his flight path and so did a building falling on him. I am comfortable with that level of power.
That is an unrelatable alien to me.
I found Cavill's Superman more relatable than Chadwick Boseman's Black Panther, even though I am black myself. The stuff like being taught to be the bigger man and holding back against bullies. Not knowing what you are going to do with your life. Searching for your reason for being in the world. Being unsure if the path you are taking is actually the right one. You know, things that have almost nothing to do with how much he can lift or how bulletproof he is. Things that everyday people go through. BP is far more susceptible to injury, that does not make him relatable to me. I have nothing in common with Chris Evans' Cap either (although I very much like the character). T'Challa is a Prince/King with the weight of a nation on his shoulders. I have no idea what that is like. The fact that he can't lift a bus does no make me see any of myself in him.
Man of Steel/BvS made Superman relatable by giving him problems he could not punch or lift. And when it was time to throw down, his enemies were on his level. You will notice that outside of Batman in BvS, who he was not trying to fight and kryptonite was involved, Cavill Supes never had a serious fight with cannon fodder. Even when he fought the League he was confused/not himself and they were not trying to kill him either.
I find your framing of relating to a character based on how far beyond superhuman they are weird, no offense. It is the person on the inside and their, you know, character that makes them relatable to me. Maybe you mean it breaks your suspension of disbelief? Or they are easier to root for as underdogs? I can understand that.
Besides, just because he couldnt press a bus over head doesn't mean he couldn't get under it and lift it with his legs. You see that on screen and it makes instinctive sense, brings in realism to the world, and makes him more present. A sense of definable boundaries is what is missing from a lot of this comic book stuff.
When you said he could not lift a bus I assumed you meant using all of his strength. Still, for a bus to be anything more than lifting a paperweight to Superman just feels like a waste to me. If a bus is very heavy for him then what is the limit for a guy like Aquaman? A Mazda Miyata? Like I said: if you want him to be weaker than a crane then just make a new character.
The way you said they need to think about Superman's limits beforehand is exactly what Snyder did for MoS. He even laid out an escalating list of what something would feel like to him. I think he said getting hit by a cruise missile would be like getting tackled by a linebacker. Sounds to me like they already did what you asked.
