Clark Kent is a better man than I am because if I was the last being from my entire race (Before he knows about Kara, of course), you better believe I would be making up the most bullshit lore just for laughs.
If I were Superman, I would just drop random lies about Kryptonian biology constantly. "Yeah- So, we're actually born from eggs. I'm an egg baby."
Who's gonna call him out? Who can tell him he's lying? Absolutely no one. You can't prove the Last Son Of Krypton wrong. You can't tell an alien that they're wrong about their own race or risk questioning them out of fear you'll come across as insensitive.
I would be lying my ass off and I would lick up every second of it.