Kamala Khan is a total superhero nerd who writes Avenger's fanfic online from her bedroom. She wouldn't just know who Carol was, she'd tell you every last thing about her. And then start on who she liked shipping Carol with the most.
Plus, I think you're underselling it a little. If you're part of saving 4 billion lives (on Earth alone), even as a relative newcomer you're going to get a bunch of attention. She's the woman who brought Tony Stark back to Earth just as point to begin. As to why Kamala focuses on Carol in particular, well there's subtext in the comics about Carol being this tall blonde with a stunning figure is kind of everything Kamala (short, teenage, slightly square and wont show bare skin below her neck) wants to be. In fact, unless I'm remembering wrong, when Kamala subconsciously shapeshifts into Carol before she has control of her powers, it's Carol's original cosutme she finds herself in - the swimsuit one with the thigh-highs, even though Carol at that point hadn't worn it in years. Carol is everything Kamala wanted to be.