Didn't the Spanish show up briefly, then come back in force later?

I've heard some speculate that this introduced European diseases, and unlike many Native American tribes, the Mayans lived in dense cities. Such disease would spread like wildfire.

(Certainly, some disease made it the other way too! Tuberculosis and syphilis are examples)

I've heard numbers like 95% died, and it was decades between first contact and serious conquest.

That leaves a lot of time for people to grow up with no one to teach them trades, or even how to read.

If we lost 95% of our population, so many active skills would be lost.