Magic being an evil force like you're thinking sounds like someone else (who is probably just as bad).
C.S Lewis maybe?
Lewis had magic-users both good (Aslan, a direct stand-in for God), evil (the White Witch, as well as the Calormen god who is a less-clear parallel for Allah), and neutral (the human Earth magician who created magic rings allowing interplanar travel). I can't recall any instances of magic being used for Good purposes
except by Aslan, though, so Lewis was probably echoing the common theme of "all magic that does not come from God is inherently evil" that was even more ubiquitous then than it is now.
90% sure Iduno is a troll, best not to engage them honestly.
I doubt he's deliberately trolling. Apart from his inexplicable mention of interracial marriage (which was definitely incorrect), his views are largely matters of personal taste. Not even Tolkien could have pleased
everybody.
Good magic however is pretty much summed up by one person, Gandalf who isn't really human.
And Galadriel, and Elrond, and Saruman (important to emphasize that he was Good for 99.9% of his career, we saw only his downfall), and almost certainly the other Istari as well. Tom Bombadil is most likely of Neutral alignment, although his magical acts that we witness are indeed Good (or at least anti-Evil).
There aren't any examples of use of magical arts by any humans at all that are good I know of.
The Fellowship visits the hilltop seat of Amon Hen, a stone throne built & enchanted by men of Gondor. While sitting in the chair, Frodo is able to see places & events at great distances; Amon Hen is essentially a high-powered magical telescope. On the other side of the river stands another hilltop throne, its twin of Amon Lhaw, which does exactly the same thing, but with sound instead of light. A magical high-powered directional microphone. While these artifacts are admittedly not inherently
Good, they are at least
defensive: Placed just inside Gondor's border to detect approaching threats. Such magical technology could almost certainly have been deployed in a more offensive/intrusive position, but they chose to keep it in their own backyard.
The superior race (of humans) arrives in Middle Earth (the explanations as to how they got superior are not relevant) and creates an advanced civilisation (Gondor) in which the regular human majority are ruled-over by the superior race. Because their superiority is biological the danger is they will mingle with inferior human stock and cause the decline of their nation, which is apparently what happens.
1. The reason for Numenorean superiority is
very relevant: They were granted longer lifespans by Illuvatar, and taught various arts by the Elves of Valinor. In other words, their superiority was
not innate, it was a gift--a gift which, incidentally, the Numenoreans had done little or nothing to
earn.
2. The only thing "biological" about their superiority is their lifespan, and even that's not much of a hard wall. Sure, you could say, "the less-cultured Men couldn't learn magic because it takes like 50 years of practice to be able to cast even a simple spell," but of course the flip side of that is "the Numenoreans didn't learn magic because nobody wanted to waste 50 years of their life, so they all got
real jobs instead."
3. The declines of Gondor and Arnor
weren't caused by intermarrying with the locals, they were caused by poor structural & military decisions. Earnur Last-King of Gondor rode away to deal with an invasion of Easterlings
without leaving an heir at home, and the king of Arnor split his realm into three to divide between his sons--the resulting smaller kingdoms were nationalist & didn't have each others' backs, enabling the Witch-king of Angmar to defeat them one at a time.
Tolkien is not about racism, it's about tribalism which is completely different.
Precisely. Sure, Boromir believes that
his nation is the greatest realm in the world, and that he himself is its greatest son--but the exact same could be said of Legolas, or Gimli, or (after he got Back Again) Bilbo, or (at least the "greatest son" part) Aragorn. Every major character knows and respects his own ancestry, his own homeland, and his own people. And while Tolkien's works do contain racist themes (how could they
not, when it's literally Elves vs. Orcs), they also contain enough
counter-examples to balance it out: Like Boromir claiming that the Men of Gondor are the strongest & noblest people in the world when there's a bunch of Elves
right there, and how the enmity between Dwarves & Elves has always caused nothing but trouble for both of them.
But enough of racism, this is a
magic thread. And while the concepts of "good" magic and "evil" magic are worth discussing, what I find more interesting by
far is the idea of
sphere-based magic, where Good and Evil are purely subject to interpretation. And to cater it to Clatch's original suggestion, we could make certain races (the playable ones) able to access magic primarily though faith-based sources (gods) or research & experimentation (libraries, slabs). This would be very familiar to players of almost any RPG. Meanwhile,
other races (night trolls, blendecs, etc.) could get their magical abilities through
natural sources--most likely tied to and powered by the sphere(s) controlling the biomes in which they live. If the occurrence/intensity of each of these two (or even better, three) types of magic could be controlled by worldgen settings, it would be easy as pie to create a world in which vampires & werebeasts roam freely, but praying fervently to one's gods and studying the secrets of life & death do nothing.