The question may be meant seriously, but it’s so outlandish to me that I don’t even know how to begin answering it. They are so clearly, starkly, physically different from one another, I can’t even imagine why you would ever consider treating them interchangeably.
You realize that is almost exactly the same language used to justify segregation and apartheid several decades ago.
They even had "science" to back it up.
If the only excuse one has is that something is physically different...but all other things being the same (for example, they all have families, build cities, have the same culture, etc) and the excuse falls onto looks only...well...some very icky reading from several decades ago about why segregation was not only necessary, but scientifically backed up (and the same could go for slavery) would quickly show that these are the same reasons people justified racism for a LOOOONG time.
It was much better when the difference between monsters and humans was not justified due to looks, but due to the very nature they were composed of.
A comparison would be between that of a Polar Bear and a Human. Sure, you can try to reason with that hungry polar bear over there, and try to treat it as your best pal, but when it gets close there's probably going to be a LOT of painful screaming from the Human, or that human better have a way to defend themselves.
The difference between a Polar Bear and a Human boils down to the very nature of the beast and what drives them to act. The Polar bear is inherently more dangerous than the single human if based on normal circumstances. It is not a creature to be pals with and one that is hanging around Human towns is probably one the Humans want to get rid of.
This could be held with many other creatures...such as Tigers or Lions who get a taste for man. Crocodiles in the River...etc.
This is the same template applied to monsters in Early D&D, and WHY monsters were seen as such.
HOWEVER, in typical irony, as seen in real life and occasionally modules...though creatures, animals, and monsters may be dangerous, ultimately the greatest evil tends to stem from man...
And that too is the difference between a Polar Bear (or Tiger or Lion) and Man. Polar Bears are acting as their nature drives them, and as such are a threat in a direct physical sense when you see one. They are even, to a degree, highly predictable because they share that nature with one another. Man, in his chaotic way is FAR more unpredictable and though perhaps not as physically menacing...is able to do FAR GREATER evil than any Creature, animal...and even in fantasy...most Monsters.
At the end of the day, in BECMI's Basic module first introduction...it isn't the goblins you truly need to fear...but Bargle himself!
PS: But then, times have changed since BECMI was made, and today...and how monsters ability to act and their relationship to humans, animals, and other things have also changed. Instead of viewing them more as we view how animals would act on their nature, we tend to view them more as how we view humans act on theirs...and in a way...that has changed a LOT about how we should describe them and publish about them today, which I think has a great deal of strong feelings in any direction you travel as this thread seems to make obvious.