The way it works, is that all these creatures simply knew Common all along, they simply didn't want to talk to you. Speak With Animals is Enchantment - it compels them to speak.
So too, is it, with all things on this world. They could talk to you, if they wanted. But they don't. Nobody wants to talk to humans. Nobody wants to talk to you in particular. Humans are notoriously horrible. You're particularly horrible.
|It's not that they can't talk to you, |
it's just that they think your whole species are jerks.
They're probably right.
Things dislike speaking in varying degrees. "Non-intelligent" animals dislike it quite a bit. You eat them for food and destroy their habitats, so of course they don't like talking to you. Insects and worms even more so - communication risks immediate squashing. Dogs are too nervous. Cats are just jerks.
This rock doesn't like you.
This is why Speak With Earth is such a heinous spell. Whereas Speak With Animals is merely unethical - compelling sentient and intelligent creatures to have awkward conversation with you - Speak With Earth is grotesquely cruel and heinous. This is typically why, when Speak With Earth is cast, more aggravated stones will be willing to throw down and crush that arrogant wizard to a pulp. Hence the necessity for....
JOE SHMOH'S MINERAL SCALE OF HARSHNESS
HOW WILLING IS THIS ROCK TO THROW DOWN?!
Mineral / Rock
Willing to Throw Down If You...
Attempt Rock Genocide (Most egregious)
Actively try to destroy it*
Speak With Earth + Make serious threats
Speak With Earth + Insult its mineral mom.
Cast Speak With Earth
Piss on it
Step on it
Converse with it by any means
Exist in its presence (Least egregious)
*Note: this doesn’t necessarily mean crushing it. Some rocks (mostly non-gems) are more chill than others with being ground up. Things that “destroy” rocks: atomization, separating it from the earth, dissolving in acid, etc.
|This is Talc. Don't step on it.|
Calcium: You may as well be another rock, for all it can tell. Also: Do not attempt rock genocide. It will end very bad for you.
Diamond: Stoic and uncaring, provided you don’t try and shatter it
Sandstone: Composed of many many compacted minerals, it will only really get mad if you try and annihilate it.
Topaz: Most noble of gems! Elects to fight duels when threats are made.
Marble: It is a noble stone, far above common insults.
Gold: Most royal of minerals; hence, it takes no insults from peasants.
Feldspar: It really just likes its mom.
Zirconium: It sits right in the middle of all Scales. The centrist of minerals.
Calcite: It really doesn’t like being wet. Vulnerable to acid.
Cement: The walls and roads of the ancients are notorious for animating and breaking in half those who would tear them down.
Osmium: Doesn’t like being touched.
Obsidian: **Exception is if you’re picking it up to use it for war and carnage. It’s pragmatic like that.
Talc: Softest of minerals, hence with the most the prove. Very aggressive and quite pitiful.
Corundum (Ruby/Sapphire): The crystalized blood of the mammalian and mollusk gods hate each other and everything else with a divine fury.
Sulphur: This stuff is PISSED.
Uranium: Normally, it just tries to kill you by existing. Enough of it gathers in one place, however, and it’ll animate to radioactively stomp your ass.