Besides.. Kal-El would probably never develop musles as strong as other kryptonians, he grew up on Earth after all.

Like I said, their tech over a long long long time is so advanced that the GUT is as remote as fire to us. They probably just are able to break matter down into energy. And also because they’d know what they were doing a “hyperdrive” wouldn’t take anywhere near the energy we’d think it would, along with antigrav and other stuff.

But IMO the more or less classic Silver-Byrne era Superman was the best.

That is that Krypton was a long, LOONNNGGG lived civilization and literally had a “Golden Age” when they were like gods but fell from that state in the dimmest recorded past. That is, it used to be like Earth’s sun, just formed earlier, and became a Red Giant.

So, why aren’t they cooked?

Well, let’s look at how Jor-El designed the “Phantom Zone”. A single scientist working out a basement universe in his home lab. They are so advanced that to them the “Grand Unified Theory” is as dim in the past as the invention of fire to us. Given the “Phantom Zone” alone they could easily have had some kind of automatic system to gradually shift their world’s orbit as the sun grew, or suddenly shift it if it suddenly went big.

Thus the planet is saved and into a stable orbit to have a similar amount of heat/light for it’s final age, around 300-600 million years before the final burn down to white dwarf.

(it seems the science end changes that story every year, sudden or gradual main sequence to red Giant stage…the length of such a period)

So they had this metabolism evolved or more likely designed to take energy from the sun, but it wasn’t optimized for other star-lights and they’d had a period of decadence and forgot how/what it was when their sun shifted.

Also to survive at all that long they have a “Conservative” culture that re-re-re defines the image of that term. Thus when they faced their world’s doom they literally chose to die for if they moved as desperate refugees through space their culture would be threatened and therefore their lives as surely as death.

In the Animated series in the 90s they had a good thing going with Braniac being the world computer system. It realizes this about their culture, that if it revealed the danger they’d try to save their entire culture and run out of time. The computer essentially decided to live so hid the truth… assuming he was hiding it… Perhaps he made a deal with the council to be released (he was essentially a slave, facing death for not obeying orders) in exchange for someday re-creating their culture on another world? The philosophical block he used to stop Jor-El from sabotaging him at the end argues this; “Temper temper Jor-El. you could destroy me, you know where to shoot, but consider… I hold the memory of Krypton. All the history for countless years. Who will know that you have ever lived?”

I like how despite it being a simplistic kid’s comic book that counted on it’s readers “Growing up” every 5 years, it having some good sci-fi inserted.

The later “Clone Wars”/Black Zero element for instance.
“You said Krypton rejected religion, save for respect and novelty to worship science. But you also said that you were at war for 100,000 years over religion…”
“Yes.”
“But how?”
“It was religion in that it was a … manner of principal.”
“Over what?”
“An aspect of our technology.”
“What was that? Something too advanced for us?”
“No, it’s something you will develop very soon. I’ve decided I have no right to interfere.”

(They cloned themselves then when they lost a limb joyriding they just had another. Or, if they wiped themselves completely they had personality backups daily as they slept. Black Zero was a pro-clone terrorist movement. Eventually they got it so Kryptonians had 3 clones each, no more. Then -Byrne Retcon- they wiped out the city of Kandor and eventually Kryptonians used life preserving body-suits.)