It could be that Manga Rock has run into legal troubles and had to remove its manga content. Or, there might be server problems or maintenance going on that's preventing you from finding what you're looking for.
Naruto had books that were sold in the form of novels, such as Naruto Gaiden: The Seventh Generation of Naruto and Maroon Flower Moon, Naruto Gaiden: The Secret History of Naruto, etc., which told some supplementary stories and characters 'experiences in the world of Naruto. However, it should be noted that these novels were not written by the original manga author, Kishimoto. I hope you like my recommendation. Muah ~
Another factor could be that in some cases, leaving manga uncolored allows for more imagination on the part of the reader. They can envision the colors in their own way. Plus, it's a traditional approach that has been followed for a long time in the manga industry.
Definitely. 'Cowboy Bebop' is a notable anime that wasn't a manga first. It has its own distinct style and story that was developed specifically for the anime medium.
It might go against the core beliefs or values upheld by Christian teachings. Maybe the content is too violent, immoral, or doesn't align with the message of love and kindness.