Are hrothgar and coeurls related?

[Cilia]

I've been wondering for a while what exactly the deal with all the sapient species in FFXIV is, actually. Given that they (most of them...) exist on the First as well means they predate the Sundering, so does that mean they existed alongside Amaurot? Came after, and were the "new life" that's constantly alluded to after Zodiark's summoning?

It hasn't been clarified, but it's been at least implied that the races of man we're familiar with sprang into existence after Zodiark stopped the Final Days.

Granted we only have a single window into pre-Sundering existence (and it's a heavily biased one at that), but there's no conclusive evidence or even known account of world population prior to the Final Days / Sundering.

In response to OP's question, there is no known link between Hrothgar and coeruls, just as there is no known link between Miqo'te and cats (or coeruls for that matter), Viera and rabbits, or Lalafell and popotoes.

[Kirika-]

or Lalafell and popotoes.

My fried Lalachips say otherwise........

[DeirdreLeaf]

But then WHY do some Hrothgar have the couerl whiskers if they don't serve some similar function?

[MikkoAkure]

But then WHY do some Hrothgar have the couerl whiskers if they don't serve some similar function?

"Because the devs wanted it" is the reason why a lot of stuff exists and most of the time it's not any deeper than that. Even the lore creators have just thrown stuff in because they felt like it without meaning for there to be any deeper meaning. The reason why Heavensward is full of dinosaurs? World-builder Banri Oda REALLY likes dinosaurs. Why do some hrothgar have couerl whiskers? Hrothgar are cats, couerl are cats, and an artist or dev probably just wanted to throw them on them because they can and it's probably not any deeper than that.

[Cilia]

But then WHY do some Hrothgar have the couerl whiskers if they don't serve some similar function?

Watsonian answer? They might serve a similar function. There's no known in-universe reason for them though; every race has human physiology unless otherwise noted though, so they may serve no biological function or a similar function to cats' whiskers. (While there is no known link between Hrothgar and coeruls or cats of any size, that doesn't mean they can't coincidentally have physiological similarities.)

Doylist answer? They're totally there to be reminiscent of coerul whiskers, as well as serve as a stand-in for facial hair on that Hrothgar face. They're there to serve as a mustache, helping to sell the idea of the man-cats.