This site usually has useful information:
Here's a couple for you, found by googling with keywords "history of idioms":
"Let the cat out of the bag" - The most reasonable of the two historical explanations for this phrase actually ties into another one involving mammals and bagging — "a pig in a poke." Dating back to around 1530, cats often served as sneaky substitutes for their porcine peers when shady businesspeople tricked their customers. Clever consumers who exposed their deception eventually spawned the familiar idiom, which retains a similar, albeit broader, meaning today. -- phrases.org
"Cat got your tongue?" - The English Navy used to use a whip called “Cat-o’-nine-tails” for flogging. The pain was so severe that it caused the victim to stay quiet for a long time. Another possible source could be from ancient Egypt, where liars’ and blasphemers’ tongues were cut out and fed to the cats. -- grammarly.com
I use www.phrases.org.uk because the research is done quite well there.
There are plenty of nonsensical explanations for idioms, so whatever you read, "take it with a grain of salt". ;)