Again though this is a fantasy setting. You can easily imagine a world populated by humanoids of varying intelligence with different brains (and that isn't a commentary on real world people at all). You are trying to imagine a world where monsters are actually part of the setting. So you can have a like orcs that are intelligent, but maybe less so than humans, and maybe more aggressive or even just natural enemies of humans. There are different ways to approach this. I don't think doing so means you are trying make some kind of real life extremists game. Now it can be done in a racist way or a way that promotes racist ideology (there is a notorious black metal musician who made an RPG and from what I have heard about it, that is what it does). That would definitely be objectionable in my view. But there is a long tradition in science fiction and fantasy of treating these kinds of things as thought experiments. And an orc in D&D is just a thought experiment. I think the problem is somewhere a long the way, some started to view orcs as stand ins for real people or even for real world ethnicities (and I get their is debate about their origins and how they were originally depicted in Tolkien's notes but by the time you get to the 70s and 80s, orcs are just monsters, not in any way a representation of a real world people).
A lot of this also hinges on alignment and how that is dealt with, which has changed a lot over the editions, as have orcs (they have been pretty different in each edition). And one challenge D&D has is carrying over its old lore and concepts into the changes in a way that can do things like accommodate different styles. So I think sometimes the PHB chooses means that aren't entirely logical but can be hand waved because once you get into the specifics of a campaign or setting you sort of choose your course from there.
With orcs and alignment, before it used to just be Law, Neutrality and Chaos and creatures like elves and orcs were more like out of Three Hearts and Three Lions, where you had these mystical beings that were aligned with the cosmic forces. One of the key differences though in Anderson is elves I believe would have also been aligned with the forces of chaos. This made these races interesting in my view because it made them somewhat incomprehensible and frightening (which I think was effective). But you see that approach in the early versions of D&D. Then when you get the more complicated alignment system, I think that is where people often disagreed over this stuff (and now we may be debating if evil orcs are racist, but even back when I first started people were arguing that it wasn't particularly realistic, especially because no one my age read stuff like Anderson so we had no sense of context).
Personally I've always found the AD&D alignment system kind of wonky but I get that people find it convenient. What I recall emerging more and more was using alignment less as an inherent or cosmic quality and more cultural tendencies so you could have things like evil empires and evil raiders (which I would argue are useful for a large number of fantasy campaigns). So the way I read an entry like C/E next to race or in a stat block for a kingdom, was these were just the tendencies (you would still find good people among them). With orcs you can just read that as this is how the trajectory of orc societies progressed in history and to human eyes they engage in evil practices (and evils would be things like engaging in slavery, killing innocent people and having a general disregard for life, etc). Again I am not saying that is the greatest world to have, personally I actually prefer orcs that are a lot more nuanced in my own games, but I get why its there in most of the editions, and I don't think it is racist, it is just a gameable conceit to have fearsome enemies who look terrifying and act terrifying for low level characters to face.
