Are you trying to write FANTASY or LITERATURE?
Superheroes are a power fantasy where the reader vicariously experiences being the Awesome Guy. For Awesome Guy to be perpetually awesome, he will always be winning and leveling up. Forever.
Consider another archetype from another kind of fantasy, the Pornstar. She is always ready for more, never satiated, never tired. If you stopped to think about what motivates her – which you don't – she must be having a disappointing experience with all that sexual activity because she is just never satisfied. You can line up a gymnasium of volunteers, or they can come in orgy groups and kinky flavors (even repulsive flavors), but they cannot defeat her. She is never finished. She will always be horny and leveling up. Forever.
These characters are "iconic". They stay in one place while the plot and other characters flow past them, like a river. James Bond is always James Bond, a vicarious ego-projection of the Awesome Guy fantasy. The villains and the babes cycle through, but James Bond is never defeated, he just keeps winning and leveling up.
Fantasies don't need to make sense, and they don't need to be explained. The reader can "drop in" on the character at any point and experience the fantasy. You have all the freedom to ignore gravity, physics, motivation, economics, consequences, and muscle soreness. I'm not trying to sound harsh, fantasies are healthy and fun, but they are more like an emotion, or an adrenaline rush, than "literature".
Literature has a message that outlasts the narrative.
These are broad definitions of "fantasy" and "literature", but consider them two ends of a narrative spectrum. Where fantasy is escapist and consumable (if not disposable), literature is grounded with realistic characters who face consequences of their actions. Fantasy is consumed like potato chips, literature is digested slowly after the meal. Literature needs to survive fridge logic while the reader processes a more complex experience.
Having a message subverts the fantasy. If there are consequences to character actions, and protagonists develop and learn and change, or suffer by their hubris, there is inevitably a message that lingers after the adventure is over.
In Greek mythology, Icarus gets to experience the fantasy of flight, but he flies too close to the sun, his wings melt, and he dies. The parable entices with a power fantasy, but ends with a message: "Don't get cocky, Flyboy." Notice that Icarus does not come back with a try/fail cycle until he "beats the sun". Icarus dies, the end. Actual consequence = gravitas. If Icarus figured out how to trick the sun so he could fly higher, the story would lose any meaningful message – it would just be a fairytale.
You can "dial in" levels of fantasy and literature, but consider how literature's message tends to be a wet blanket on the fantasy, while fantasy's (cough) indulgences require suspension of disbelief (if not complete rejection of reality). These two elements counter each other – while they can co-exist in the same story, ultimately it leans one-way or the other. A story can have fantastical elements and still convey a message, but too much of one spoils the other.
Going back to the pornstar analogy, when the main character evolves and grows from their experience, it stops being pornography. We can split hairs over terms like "erotic fiction", but once the character has an arc and a message or meaningful consequences appear, it's more than just a basic sex-fantasy. Even the 50 Shades trilogy rises above pornography by giving Christian Grey a character arc (too bad about Anastasia but she's not the main character). It's not deep literature, but most people know the difference between erotic fiction and fantasy porn when they see it.
Think about whether you ultimately want a fantasy about a superhero who is perpetually leveling up, or literature where the hero sacrifices and changes to convey a message that can outlast the narrative.