Even being able to write your name was uncommon through the 1600's. Literacy has changed a lot in the last 200 years.
In 1500's(14?) Spain, being able to read and write got you better than "I'm a computer programmer in 2000" prospects. Being able to read silently, without even moving your lips(!?!), got you rumors of deals with the Devil. Now you get to graduate primary-school, and eventually learn programming. Before the recent vast expansion in programming jobs, lots of science phds were driving cabs. Veterinary masters clean cages in zoos. Minimum viable education has been seriously escalating. Even with everything still being taught very very badly. If education tech ever dramatically improves... that'll be interesting.
The question isn't about common literacy, it's about literacy among the nobility, chieftains, clerics.
Much of that, among many other things like basic education, architecture, so many materials and methods, didn't happen until Latinization/Christianization of that part of Europe.
The period of ~1000 BC was solidly Bronze age, before the classical era or antiquity (~500 BC), before the Roman Empire, before the fall of the Roman Empire leading to the Dark Ages.
"The "Dark Ages" is a historical periodization traditionally referring to the Middle Ages (c. 5th–15th century) that asserts that a demographic, cultural, and economic deterioration occurred in Western Europe following the decline of the Roman Empire."
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