The Grimms made them gentler, not darker
The usual claim is that fairy tales were sanitised for children and the originals were grim. The direction of travel is right and the Grimms are the ones who did it — to their own book. Their first edition in 1812 was assembled as a scholarly collection for adults, and over six further editions across forty years they steadily softened it, because parents kept complaining.
The most telling change: in the first edition, SNOWWHITE's murderous mother is her actual mother. By the later editions she has become a stepmother, and the same swap happens in HANSEL and GRETEL. Killing off the real mother and substituting a stepmother was a deliberate edit to make the stories bearable — which is how a great many stepmothers ended up with a reputation problem.
Cinderella is thousands of years old and from everywhere
The version most people know is Charles Perrault's from 1697 — he is the one who added the PUMPKIN, the fairy godmother and the glass SLIPPER. But the shape of the story is far older and turns up all over the world, usually without any of those details.
A Chinese version, Ye Xian, was written down in the ninth century and has a wish-granting fish and a lost golden shoe. There are Egyptian, Indian and Native American relatives. Folklorists have catalogued hundreds of variants, and index tales by plot rather than by title for exactly that reason. The bones — a mistreated child, a hidden helper, a test of identity — appear to be something humans reinvent.
The stories are instructions in disguise
Read them as advice and they stop being random. Do not go into the woods alone. Do not accept food from strangers. Do not tell people where you live. A WITCH with a house made of sweets is a lesson about things that look too good, delivered in a form a five-year-old will remember for sixty years.
That is the job oral stories were doing before anybody could write the rules down. The frightening bits are load-bearing: a warning nobody finds frightening does not get passed on. It is also why modern retellings that remove all the danger tend to feel weightless — the DRAGON is not decoration, it is the reason the story survived long enough to reach you.
What is in the grid, and who changed it last
The Grimms gave us SNOWWHITE, RAPUNZEL, HANSEL and GRETEL. Perrault gave us CINDERELLA's PUMPKIN and SLIPPER. Hans Christian Andersen actually wrote THUMBELINA and the little MERMAID himself, so those have an author rather than a collector. ALADDIN was not in the original Arabian Nights at all and seems to have been added in France in the 1700s. GOLDILOCKS began as an old woman, and PINOCCHIO started life in an Italian newspaper serial.
The most recent editor is Disney, which is now the version most children meet first — and which gave the little mermaid a happy ending that Andersen very much did not write. Every one of these stories arrives having been rewritten by whoever told it last, and that is not a corruption of the form. It is the form.