Am I crazy to think that there's something uncomfortably cultural-approproationy about the whole "Human/Non-Kryptonian gains Kryptonian powers and upshows Superman" plot point. But, like, not for the intended reasons?
Like yeah, they take over his Thing and usually wear his colours and FAMILY crest and it's incredibly scummy. But the writers ALSO blatantly write them as being as good or better than the alien...at being an alien. Like, the fact that Clark's powers are something he honed his whole life is an extremely prominent part of Clark's relationship with his identity, but apparently he's just a chud because this random person is proficient immediately. Or they got a Super Training Program, because a team of scientists is also of course more knowledgeable about being an alien than the alien. I feel like you can't position Kryptonian powers as a stand-in for cultural/physical differences of another race/ethnicity and go "uhm, aktually, Kryptonians aren't as good at that as random people (usually depicted as stand-ins for USAmericans or straight up are) and scientists who observe it through a clinical outsider lense"
Idk, I stomach the trope way better when that person is given a way weaker immitation of Kryptonian powers and think they did something until an actual Kryptonian comes and shows them they don't know anything about the reality of it. (It's why it took me quite some time to warm up to Kong Kenan. His backstory really gave too many Blue People Avatar vibes for my liking. Except worse (or better? Is it better?!? I really don't know, objectively. It FEELS worse to me but maybe it's cultural differences. But it very much uses Kryptonian identity as a commodity imo). Instead of his mind being downloaded into a printed alien body (which is ALREADY bad and uncomfortable enough), they straight up forcefully put a part of Superman's soul/life force in him. And, again, he's proficient almost immediately, excluding some hiccups here and there. Obviously, I don't blame Kenan for that, but, like, we aren't gonna talk about the implications of it?!?! Are we not even gonna examine where that makes Kenan stand when it comes to Kryptonian identity?)
This interpretation of cultural allegory is flawed on 2 crucial aspects:
Ability. For example, the ability to jump is not a cultural act. But- if the jump was integrated into something like a dance or martial arts, where it exists within context of history, philosophy, spiritualism and so on- then that jump is recontextualized. That ability is recontextualized.
The Kryptonians' heightened abilities are contextual to their environment. Because there is no yellow sun on Krypton, Kryptonians never got to build a culture around those heightened abilities. They seem to be aware of that potential in their bodies, but considering so much of their lore is traditionally tied to them not getting to explore other planets (Krypton exploding and the only space vessel that could be made is one for a baby)- I think it's fair to assume they never got to say- design culture around flight or x-ray vision.
Think about how shapeshifting and telepathy is cultural in Martian Manhunter comics. It's portrayed with social norms and rites of passage. Or consider how bending is portrayed in Avatar the last airbender, rich with philosophy and mythological context. Kryptonian Yellow Sun Powers do not have that context. Should Clark find it appropriative when Wonder Woman flies? It's not cultural when Superman punches Ultra Humanite with super strength.
The trope you're describing of "Guy Who Is Not Part Of The Culture But Outdoes All The Cultural People At It" is generally part of the "white man going native" flavor of white saviorism. Think of things like MCU Doctor Strange. It's about a white man going to Tibet-coded place to learn mystic arts. He becomes the best at it despite being basically a guest to the culture. Or as you suggested; blue people Avatar. Where Jake Sully becomes so good at being indigenous that he literally becomes their god for landing the biggest bird.
So I find it super weird to apply this kind of reading to Kong Kenan. Not only is he textually not white, but he doesn't fit the bill of that trope's structure at all.
For one, the story is fully aware of appropriation and commodification. That's part of the commentary. Because it's not just Superman iconography that's appropriated, but that of Wonder Woman and Batman too. Heck, the whole Justice League in name is taken as well.
Never are the scientists or Kong Kenan depicted as being effortlessly more knowledgeable or capable at being Superman than Clark was. When Kenan receives his artificial Superman powers for the first time, he can't control it- it disappears at random moments. And the scientists do not know why that's happening.
I'm trying to find a nice way to say that describing Kenan's superhero-ing journey as "he's proficient immediately" "minus some hiccups" is frankly bizarre. Like?? In his first mission he was completely de-powered and told to stay in the car to watch over a little girl while Batman and Wonder Woman do all the work. Kenan then identifies with the girl's pain and decides to go out and do something regardless of his powers not showing up. Kenan gets face blasted with a sun-beam and momentarily regains his super strength enough to punch a guy. One punch is all he contributed to this mission. Kenan then spills his secret identity for All Of China To See like an idiot and gets a major scolding for it.
When it comes to ability, Kenan spends multiple arcs having to figure out from scratch how his unique manifestation of powers works for him. He attends a martial arts class with a special teacher who gives him a challenge he feels he failed to the point of being unworthy of the Superman mantle. The mentor lets him win, but only after imparting some important wisdom;
That Kenan's allowed to interpret being Superman his own way. And that way is cultural! Using Bagua to ground his abilities!!
So I don't think all that trial and error Kenan goes through could be described as a "few hiccups". He is far from an effortless exceptional superhero in terms of raw ability because he has to earn understanding of his powers to use them.
Even your suggestion about learning from a Kryptonian happens. Kenan and Clark get to bond about struggling with powers. And I find it touching that Clark doesn't actually have all the answers. We like to romanticize cultural people as unquestioned authority, but Clark's just as confused as anyone else.
"You are who you are, regardless of your powers."
So if we take Clark's words here to heart and analyze Kenan not from an ability perspective but from a moral one, what do we get? Kenan's first origin story arc revolves around him trying to make sense of what being a hero means. He starts out as a literal bully and admits he doesn't know what it takes to be heroic. What about that makes him effortlessly better than Clark?
And that's honestly why Kong Kenan is the BEST Superman legacy character. Because he stands in opposition to Superman's exceptionalism. Americans love stories about exceptionalism because it appeals to their individualistic culture. Clark may have had to work to make sense of his powers, but he was also born special. With a body that's just better than that of human beings under a yellow sun.
Kenan's powers are artificial, and so he has to work harder to understand them. He has to earn everything with the help of others. He isn't a particularly nice guy at the start of the story so he even has to work more to be kinder. His story is collectivist because it posits the idea that maybe being Superman shouldn't be special.
I get that it's because you're looking at it through a cultural angle, but so much of your ask is disgusted at the idea that anyone can be Superman. That anyone from outside of biological Kryptonian heritage is an invader to his brand of heroism for wearing the symbol.
Because as far as Superman himself is concerned? Being Super isn't a closed practice.