RWBY is soft-grimdark
You may agree or disagree with this opinion of mine, but I feel RWBY is a grimdark setting. The difference between it and other grimdark settings being that the characters are still optimistic, have hope for the future, and are trying to fight against the odds they face.
Think about it:
The twin G-ds of Remnant are uncaring all-powerful beings which have once killed an entire planets worth of people and will do it again if the relics are reunited. They feel nothing for humanity and are considered a mere experiment.
Humanity has been preyed upon by soulless monstrosities which intrinsically want to murder humanity and have done so for 10,000 years. They are also attracted to any negative emotions which half of all human emotions.
Leaving any of the main cities of the Four Kingdoms (and Menagerie) will end with you murdered by Grimm or Bandits. Humanity is caged into giant pens and are reliant on armies of children trained for combat by the Huntress System.
Speaking of Bandits, humanity is covered with Criminal Syndicates, Terrorist Organizations, and Bandit Tribes which undermine the ability to fend of the Grimm.
Racism and slavery are widespread across the planet. Faunus, sentient being are considered subhumans to a majority of humanity.
Any negative emotions attract Grimm which leads to a lack of social mobility, because protest and revolution attracts Grimm. The Faunus were segregated on a separate continent in order to prevent more warfare following the Rights Revolution.
The democracies of the Four Kingdom are a facade, with Headmaster Ozpin being the puppet master of the planet and all the headmasters, who rule their Kingdom respectively, answering to him.
When the planetary deep state is destroyed at the end of Volume 3, this leads to thousands of deaths, a total breakdown of worldwide communication, and the destruction the entire Kingdom of Atlas/Mantle.
Salem is literally unkillable and Team RWBY and friends have no solution to actually stop her, just hold back her plans. She plans to wipe out all life on the planet by reuniting the relics.
Its not just me that feels RWBY is a Grimdark where the story and characters don't treat their world as unsalvageable, right?