By this point, nothing is more cliche in academia then some mincing fruitcake in the humanities doing a Masters Thesis on some pop culture topic. GILLIGAN'S ISLAND is a big one, as is Superman. FRIENDS is also getting up there, especially among white people.
One topic that is chosen often is the idea of Superman as an immigrant. It is true that Superman has many elements in common with immigrants, such as a dual "I am this culture, but also this one, too" identity (some of the more poignant moments involve Superman and Supergirl lighting their Space-Menorah for holidays only they know), and a sense of exile and loss.
But there are also many differences between Superman's story and the immigrant experience that he cannot truly be said to really be called "the ultimate immigrant."
Such as:
Superman never had to "adapt" when he arrived on Earth. Superman was raised as a normal earth boy in a small town, given flawless fluency in English by foster parents, and as his Clark Kent, his very DEFINITION is as a bland person that doesn't stand out or is considered unusual. Superman has never had to struggle with Earth customs; he's born to them.
There's no "culture clash" in Superman's story. Many immigrants deliberately adopt a new identity to Americanize themselves (just ask Jack Kirby and Gil Kane, neither of which is their real name), however, Clark Kent came on the scene so early on that it's hard to say where he begins and Kal-El's own personality ends.
(If I can do an aside, I've never agreed with many that claim that Clark Kent is entirely a fiction that Superman adopts just for kicks. First, it's irrational for Superman to adopt an earth identity and spend HOURS a day at it just to play games. For Clark Kent to be so important, there has to be some "truth" to him. I wouldn't go as far to say that he's the "real" person as some of the nineties writers would, but that the reason that Superman is Clark Kent is because some qualities that we see in Kent are true of Kal-El as well. He can be both Superman and Clark Kent the same way you're not the same way with your grandparents as you are with your raunchy drinking buddies. If EITHER identity is "truer," however, it must be Superman, because who we truly are, is defined by what we do under pressure and Superman's matyring sense of self-sacrifice always bubbles up in crisis situations, showing that ultimately, he's more tiger than lamb).
There's no curious hybridity of Superman's Kryptonian and Earthling sense of identity. Superman keeps his Kyptonian identity, which he expresses in the Fortress of Solitude, and his earthling life as Clark Kent, seperate. An example of what I'm talking about here is that some Cuban-American families celebrate Thanksgiving (an American holiday) but they serve roast pork instead of turkey. On one amusing occasion at a girlfriend's house, her parents thought the cranberry sauce I had brought was a dessert, and they served it with whipped cream! If Superman does combine his Kryptonian ways with Earthly ones, we've yet to see it, and since Superman is familiar with earthly ways, we've yet to see it.
Superman has always seen American society as it is. It's an oversimplification of many complicated character traits in Superman's personality to call him "optimistic." Superman doesn't kill because of his belief that all human life has value, for instance, and he is a person that doesn't compromise his high ideals, but that's
not quite the same thing as someone that blinds themselves to the evil in others. At the same time, one aspect of the immigrant experience is that there is a sort of disillusionment from expectations.
One famous quote that summarizes this sentiment is "
When I arrived in America, I thought the streets were paved with gold. I soon discovered that not only were they not paved with gold, but that I was expected to pave them." Many Jewish immigrants are surprised to find that unfortunately, the United States has anti-Semites just like anywhere else. Superman, I'd argue, is immersed in American society from childhood, and so he sees America with warts and all.
As for other heroes that claim the "immigrant experience" title...
Hawkman and Hawkgirl aren't immigrants either. They got everything they needed to know about Earth from the Absorbascon (easily the most INSANE piece of gadgetry in superhero comics by an order of magnitude), and they settled into their curator jobs without a single hitch or bump. But more importantly, they are NOT here to stay; they're studying Earth's crimefighting techniques, and presumably if they get a nestful of little hawklings, they'll raise them Thanagarian, because at some point in the ill-defined future, it's likely they'll go back to Polaris. Think of it like an American student studying in Paris. He may grow to have a great deal of admiration for French culture and people, but that doesn't change who he is, or the fact he's going back in a few semesters.
If any character has a legitimate claim to the title of having the classic "immigrant experience," it would be Wonder Woman, at least the Linda Carter TV version. She could reprogram a high-end computer lickety-split, but she didn't get slang or pop culture references, and she didn't know how to dance.
Hmmm...with all her tech skills, maybe Wonder Woman might be a part of the brain drain!