A King was losing a war, so he went to a Wizard and had him create an army. The wizard only knew of golems, but their thinking was rather simple and the runic mark on their forehead was a glaring weakness, so he was forced to create something new. Automatons were created and thus changed the tide of the war. They could be made to look human to blend into the enemy army, they were also far stronger and faster than a normal human, and some of them could even perform specific spells. The King didn’t trust the automatons, after all they were loyal to the wizard, not him. Now he didn’t do anything drastic like some in his position might do and try to kill the Wizard, instead, he simply phased them out with human soldiers over time. Eventually, to humans, automatons became myth just as wizards and dragons did.
While the innovation of automatons had a rather small impact in the muggle world, outside of the war, the wizarding world was another story. Suddenly a new source of labor was introduced. Jobs that could be done with magic but were tedious were now allocated to automatons. There was a large influx of automatons that pervaded many homes the quality of which depended heavily on the wealth of the families.
Automatons were even more dangerous because they had an artificial intelligence of sorts that golems did not. Wizards however often viewed them as beneath them because they required magic from their master to survive. There are a few stories about automatons killing their master, but of course it's rarely mentioned the automaton was often abused.
[3:10 AM] Fighting had also changed due to the introduction of automatons. Wizards often stayed in the back to provide cover and long-ranged attacks while the automatons specialized in protecting the wizard and close-quarters combat. Some automatons like a dragon model had the ability to perform fire attacks. A fight would be over if an opposing wizard was subdued. Most aurors only had 1 automaton, a partner of sorts, but it was not uncommon for others to have more. However, this required significantly more magic power from the wizard.
The strength of an automaton depends on experience, materials they are crafted from, the craftsmanship of their parts, and the amount of magic given by their wizard. A wizard can boost the magic they give an automaton increasing their abilities. Too much magic power can damage parts, hence the need for better parts.
Harry found more than just gold when he visited his families vault for the first time. An automaton stored in the vault activated upon his arrival. According to Hagrid it was a Veela model; mainly ment for child care or maid work. The weird thing was that Fleur, the designation given to the automaton, didn’t even know how to properly eat or how money worked let.
Harry took it upon himself to teach her how the world worked. It wasn’t until Harry got to Hogwarts and was promptly challenged by Malfoy that he learned Fleur specialty was fighting.