So... a thing I intend to do, going forward, and a thing that WotC should do, is make creatures, even humanlike ones, that cannot alter their moral position "Unaligned", and then let their actions determine morality as things happen.
Angels and Demons? Unaligned Outsides. Angels might foster goodness in the universe, might -serve- goodness or a good creature... But they do so not out of choice or moral compunction, but because they're designed to do so. Further, they can and will commit terrible acts of horrible evil in order to fulfill the intentions of their creators.
An Angel will burn an entire city to the ground if they are commanded to do so, with no pause to rescue children or ensure that animals are loosed and saved, because they have been told that it will be good to do so.
Similarly, even a demon acting in a manner that appears good, such as saving a family, is ultimately serving a greater evil. And has no more moral consideration for the act than for poking a hole in a chicken.
Redcaps? Murderous Unaligned Fae. They kill because it is what they do. They're not "Evil" or "Good" or even "Neutral" because those alignments imply there's some morality to their thoughts and deeds. There isn't. No more than there's thought to their failed attempts at Stealth while wearing iron boots that they never remove. If a Redcap wanted to be stealthy, he could take them off. But even when he wishes to be stealthy, the boots make it basically impossible.
Because like homicide, the boots are a part of what a Redcap is.
As to the racial allegories of Redcaps: are not "People" or Representations thereof in any example. They're explicitly, historically, mythological monsters. So trying to compare them to things like Orcs and Elves is doomed to failure. And there's actually a couple of layered reasons for that.
Firstly: Orcs were never mythological. They were created, whole cloth, by Tolkien and other writers. There's no cultural tradition of Orcs in myth and legend unlike the Powrie/Redcap. Orcs were created to represent Corrupted Elves. Which is -already- heavy into racism because the Orcs are Black (With Black Speech) while the Elves are all white and blonde and it plays hard into Ham, of Biblical fame. Oh, I'm sure Tolkien didn't sit down and think "Darn black people and/or Jewish People, I'mma make them my villains!" when he wrote the book (though I could be wrong)
But there's a long-standing cultural precedent of "Evil = Black Skin" that Tolkien had been exposed to. And pretending it ain't there is foolish.
But then future writers took his evil orcs and gave them societies and personalities and families and made them even more humanlike. Which just -exacerbates- the issue. Because now you're applying all the cultural traits of various societies to the "Evil Race". Which are, almost invariably, 'Primitive' and 'Tribal'.
Meanwhile Elves -were- a Mythological race of people who were good, evil, and in between. At least from the cultural understanding that we (And Tolkien) could reasonably be able to gather. He was, after all, an abject nerd who studied linguistics and stuff like we study RPG Texts... And then we turned around and redid the Curse of Ham with evil black elves transformed by their gods. But elves themselves? They were always meant to be allegorically similar to humans with their own societies and identities and ideologies.
The Powrie are neither of those things. They were always an evil mythological bogeyman. They've got no cultural traits that reflect any society, and aren't geared to represent any specific race, except -maybe- White Irish people in a very specific region who were murderers and bandits during a specific period of time which gave rise to the myth.
In the event that Redcaps are instead written to have a specific culture with their own identity and trappings, and/or the ability to make moral choices, it'll be a social issue. But until then, they're no more humanlike than the penanggalan, even if they've got a more human form.
And they should be, as previously noted, Unaligned homicidal murder elementals. It makes all the sense in the world.