Yeah, the machines that they smashed had been in use in England for 2 centuries at that point. It's very unlikely that they just decided to rebel against this 2 century old "new technology" because they were some primitive brutes as they are depicted. History is written by the victors, and in this case capitalists were successful in tarnishing their reputation for centuries.

Not just "worried about losing their jobs to automation". They were trying to get the government to enforce laws that protected their jobs, but the government refused to do it.

As with most manufacturing at the time, there was a guild system in place where new workers went through an apprenticeship and after they proved their mastery by creating a masterpiece, they were acknowledged as master craftsmen and could work on their own. This was enforced by laws like the Statute of Artificers of 1562/1563 that required that apprentices work for a mandatory 7 years before they could move up.

The workers didn't mind jobs being done by machines. They just wanted the machines to be controlled by people who were in the right guild and had gone through the proper period of apprenticeship. That would result in the quality of the end product meeting the standards of the guild.

Because the government refused to enforce those laws, the guilds took matters into their own hands. They led loud protests and strikes. In France the workers at these protests often wore wooden work shoes called "sabots", so the French coined the word "sabotage" for these protests. Since the protests weren't enough to get the government to enforce the laws, the workers attacked factories that were producing low-quality textiles made by low-paid employees who weren't members of the guild and broke the machines by smashing them with hammers.

Instead of convincing the government to enforce existing laws, that resulted in the government passing new laws protecting the machines (stocking frames) used to produce the textiles, and eventually passed a law allowing the death penalty for smashing a stocking frame. As a result, the workers didn't want their real identities revealed while they destroyed the machines. So, they claimed they were following the orders of "Ned Ludd" or "King Ludd", who lived in Sherwood Forest.

It's true that, to a certain extent, the workers were trying to stop technological progress in order to protect their jobs. But, mostly, it was an attempt to keep their fair share of the profits from doing the work. They didn't mind that the machines existed. They just thought that the machines should be operated by a master craftsman instead of an orphan child, and that the final product meet the quality standards that the guild demanded. Meanwhile the owners of the factories and machines were basically trying to use the machines as a way to break the control the guilds had over the manufacturing process and to have as little money possible go to the workers, and as much as possible go to the owners of the machines.