Only one. And as @shaddack inferred, sample size is everything.
Here on Earth we have a sample size of millions of different organisms, over millions of years, and only one of them developed intelligence(1), and that seems to have only happened because small, shrew-like mammals got a lucky break. If the dinosaurs (amongst others) weren’t wiped out, I’d wager my birth that Earth would still be a wild and overgrown place.
I think that it’s wrong to compare it to exceptionalism. That’s a strawman. Or possibly a red herring.
(1) As intelligence is a little slippery to define, I’ve used ‘the ability to actually work out what those lights in the sky are’ as my yardstick.
