I think Drakus is correct in saying that the Haradrim and other folk of the east and south were only "evil" in that they had had little or no contact with the Valar or their representatives. We know that some of them had been ruled by or dominated by the Black Numenoreans and had long been under the sway of Sauron in the Second and Third Ages. But they also continued to wage war against Gondor and its allies into the Fourth Age - long after Sauron's fall.

Two of the 'Wizards' or Istari, the Ithryn Luin or 'Blue Wizards' are said to have "passed into the East", though what their mission was or whether they had any impact on the men of that region is unknown. Gandalf was known as "Incanus" amongst the Haradrim, and it's known that he travelled in the south. Aragorn campaigned in Harad early in his life, raiding Umbar as a captain of Gondorim under the name Thorongil in 2980 TA.

The Haradrim were known as 'Southrons' or 'Southerns' in Westron and as 'Swertings' in the Shire. This last word is pure Old English and means 'black ones', though it should be remembered that 'Swerting' is also the name of a character in Beowulf, where it is likely to refer to the colour of the character's hair rather than their skin. The passage in "Of Herbs and Stewed Rabbit" where Sam and Frodo see a dead Haradrim up close indicates they were darker-skinned than people of the north, with dark eyes and black hair.

I would also second Drakus' caution about looking for what races or characters in LOTR "represent". Tolkien took a dim view of simplistic symbolism or outright allegory and generally displayed impatience and annoyance with people who tried to find out what his books "meant" or what things in them "symbolised".
Cheers,

The Venerable Thiu