Grammatical number in English is horrible, and we should just give up on it. Granted, this is something we can say about basically every aspect of the English language, and there's a queue from here to Worcestershire to grouse about our horrendous spelling, but I feel the dreadfulness of our plurals tends to go unnoticed.
First off, we have our pronouns. The first person is straightforward with "I" and "we". Well, unless you're royalty, but that's rare enough to ignore. The second person made sense once upon a time, when we still had "thee" as its singular, but now it's all just "you". There is also "y'all", but for reasons that probably boil down to classism, a lot of people have a problem with it.
The third person used to be straightforward. The only confusion was in the singular, where "she" could refer to either certain inanimate objects or women (who men wished were inanimate). From the 19th century, when prescription of "he" as the generic singular really got started, through the turn of the 21st, things were simple. There was order, there was reason, there was misogyny. But, fairly recently, we've started getting this bizarre notion that women matter, and maybe we shouldn't assume a non-specific person is a man. Thus, we saw the return of the singular "they", and the weird grammatical gymnastics it requires. On top of that, we've just started to realize there are far more genders than English is remotely prepared to deal with. This means using "he" or "she" (or even "he or she") could still be factually and grammatically incorrect. While there have been attempts at adding new pronouns for enbies to use, they've all kinda fizzled (I'd say partly because there are too many). This leaves us with no choice but to accept the inevitable rise of the singular "they".
This, alone, I would consider sufficient evidence that communicating number in English is absurdly complex. Clearly, to do so for people is just not a thing we'll even be able to manage at all. But this barely scratches the surface.
Look at "everything". Despite meaning multiple things, it's singular because you're referring to each individual thing by itself. Sure, you get used to that, but if you think it's intuitive you're kidding yourself. And British English will refer to a company as plural ("Apple are courageously removing the headphone jack") because it's a group of individuals, but in America a company is singular ("Apple has outrageously slaughtered the headphone jack"). I guess this is because in America, corporations are people, my friend.
We also have phrases like "notaries public", where we pluralize the first word of the phrase rather than the second. It's because the latter is an adjective, of course, but if we're going to violate the rule that the adjectives should come first, why can't we violate the rule about which one gets pluralized?
Then we have words from other languages, where the choice about whether to use that language's own plural seems to be entirely random. You can say "indexes" or "indices", "emojis" or "emoji", "paninis" or "panini"; it depends only on how much smarter you want to sound than the person you're talking to. And you can go right ahead and say campuses, but don't you dare say alumnuses.
Clearly, grammatical number in English is a convoluted disaster of inconsistent and meaningless rules. A thorough understanding of them must surely come only from steeping in their senselessness long enough for them to gain an illusion of logic. I would humbly propose that we simply do away with number entirely. If everything are plural, nothing are confusing at all. With these one simple change, the English languages will make much more senses. Besides, we're already fine with just calling pants, scissors, and glasses by the plurals all the time, and deer, fish, and aircraft by the singulars, so would we really even be missing anything? Sure we might sound like those ones characters from Futuramas, but we'll save ourselves some lots of hassles.