Actually, I disagree with this. He's born as Kal-El, but he's raised as Clark Kent. I like the interpretation that Clark Kent is not a disguise or a mask at all, but it's who he really is, and how he sees himself.

This doesn't match up with all interpretations and tellings of the Superman story, but I prefer the idea that neither persona is a mask, and that what's unique about Superman is actually that neither identity is really his "secret identity". When he's Clark, he's a moral, straight-laced farm boy who always tries to do the right thing, in as much as it's within his power. When he's Superman, he's a moral, straight-laced Kryptonian who always tries to do the right thing, in as much as it's within his power. In reality, he's always a farm boy and he's always a Kryptonian.

So what's interesting about this interpretation is that both identities are the same, except for how he dresses and what's "within his power". The implication is that Clark Kent is an everyday hero who is exposing himself to as much risk as Superman, but without the recognition.

I might imagine this interpretation of Superman noting at some point, "If I walk an old lady across the street wearing street clothes, it's just a normal event and nobody cares or is impressed. In street clothes, I'm just another nerdy, up-tight guy who people ignore. But if I put on a red cape and walk the same old lady across the street, it makes the nightly news. I'm not a different guy. I'm not doing a different thing. But suddenly people lose their minds because they know I'm someone who's supposed to be important."

I think that kind of interpretation of Superman makes him much more interesting. It also makes his interest and rejection by Lois that much more poignant, even if it does make her look more superficial. Superman becomes a stand-in for anyone who feels left-out, disregarded, or ignored because others are too superficial to see past a set of glasses (or what those glasses symbolically mean), while also simultaneously standing in for those who feel like other people only like them and pay attention because of their wealth, power, good looks, social standing, etc. He manages to serve both roles.

And I think that's also very important for his struggle for perfection, in that he's constantly being judged. He suffers unfair judgments from others across the whole spectrum of unfair judgements. The same person might think that Clark is too weak and that Superman is too strong. The same person might think that Superman gets all the breaks while Clark Kent is a total loser with nothing going for him. And there's even a reality to those judgements. Lois loves Superman even though Superman doesn't really deserve that love, while she dismisses Clark who actually does deserve that love. Clark has to see all of that, and then cope emotionally with having to be not-just-perfect, but even having to be both sides of the same coin. He has to be perfect, and earn his place in the world, both as the strongest man on earth, and as a weakling.