Interesting thread!
I did not know the huns were the original uruks.
In Tolkien, of course, the Black Uruks or Uruk Hai were the elite of the orcs - man-sized, (where normal orcs were smaller), smarter, braver, more aggressive, more disciplined, and not afraid of sunlight.
The Uruk Hai were also used as overseers of the other orcs, maintaining discipline, and preventing fighting between the different tribes.
And they were definitely not green. The Trolls were green.
Fellowship of the Ring was a great book! Saying that makes this a critical review, which allows me to quote a brief passage
This is from the battle in the chamber of Mazarbul, in the mines of Moria, bottom of page 422 in my version. The chapter name is "The Bridge of Khazad-Dum".
"But even as they retreated, and before Merry and Pippin had reached the stair outside, a huge orc-chieftain, almost man-high, clad in black mail from head to foot, leaped into the chamber; behind him his followers clustered in the doorway. His broad flat face was swart, his eyes were like coals, and his tongue was red; he wielded a great spear."
Whew, the man sure was fond of commas and semi-colons, wasn't he?
Anyhow, the key word here is
swart. According to my huge old unabridged dictionary,
swart is from Middle English
swart (same spelling) and that from the Anglo-Saxon
sweart, both meaning literally black.