I see the Firstborn as embodying all of humanities’ traits, magnified. Far nobler, wiser, stronger than we are…and far more pigheaded, arrogant, and just plain dumb!
My daughter says that Feanor, as fascinating as he is, is one seriously scary dude. I concur.
Well, per JRRT, the elves were comparable to men who had not fallen from grace. You, know, all that “original sin” stuff was lacking in the Firstborn. I’m not enough of a theologian to decipher out what that means, but it tends to get translated as “nobler, but still having all the fundamental character defects inherent in mankind”.