The RWBY manga doesn't manage to fix everything that was off in the show. It does make some efforts, but it's not a comprehensive solution to all the show's shortcomings.
Distant Marvels is fiction for sure. It has elements that are beyond what we encounter in the real world, crafted solely for the purpose of creating an engaging story.
Well, I don't actually know the specific 'the day everything went wrong story'. But generally, it could be about a day when a person woke up late, missed the bus, then got to work or school and found out they had forgotten an important assignment. Maybe they spilled coffee on their clothes during lunch and later got into an argument with a friend. It's all about a series of misfortunes that happened in one day.
One possible element could be bad weather. If it's pouring rain and you don't have an umbrella, that can start a series of problems. Another could be miscommunication. For example, getting the wrong time for an appointment. Also, technical problems like a phone dying when you need it most.
It could be a series of unfortunate events like missing an important appointment, having a fight with a loved one, and losing something valuable all in one day.
Oh, there are many! Like when I planned a perfect picnic but it rained cats and dogs, and all the food got spoiled. That was a disaster but funny in retrospect.
One key element is the origin of powers. For Carol Danvers, it was the Kree technology. For Kamala Khan, it was a mysterious event that gave her polymorph abilities. Another element is the relationships between the characters. Kamala looks up to Carol, and Monica has her own connection to Carol as well. Also, the different settings play a role. Carol's story has a lot to do with space, while Kamala's is more grounded on Earth in her neighborhood.
The Marvels' back story is quite complex. It involves different characters each with their own origins. For example, Carol Danvers, who became Captain Marvel, was a pilot. She got her powers through an accident involving Kree technology. Her powers include super strength, flight, and energy projection. Then there's Kamala Khan, a young fangirl who idolizes Carol. Kamala herself gains polymorph powers in an unexpected way, and she is inspired by the superheroes around her. And Monica Rambeau, who has her own journey in the world of powers and heroics, having been exposed to various energy sources that have shaped her abilities.