That's the thing about words, all words. There's no direct connection between a word and a meaning. It will always depend on context.
Yeah, we have many descriptions of what we call snow. White snow, yellow snow, blowing snow, piled snow, frozen snow, grizzle snow, fluffy snow, but they're all "snow." It's like saying we have lots of "words" for rain.
Of course, if I said it was snizzling outside, people might have some clue.
Oh, re social interactions, some cultures nod their head to disagree and shake it to agree. Thumbs up doesn't mean the same thing everywhere.
And, afa the monkey's smile, there's an old song with the lyric
"A smile is just a frown turned upside down.
Smiling faces, smiling faces, sometimes, they don't tell the truth.
Smiling faces, smiling faces, tell lies, and I got proof."
It is true for dogs that baring the teeth is a potential sign of aggression. In some human cultures, it's also considered inappropriate among strangers (not just a smile, but smiling a lot, the way some might think a guilty person has nervous laughter, or it's sweet, just a bit too sticky.