There are two relatively recent books that dig in on the relationship between humans and governments or states and the degree to which these were less of a linear history and more of an ongoing negotiation - Against the Grain by James C Scott focuses on early states and their semi-regular failures, and The Dawn of Everything by Graeber and Wengrow talk about the ongoing process of power negotiations between the putative leadership class and the citizenry. Both emphasize the same thing: that retrenchments against the state were a regular occurrence, and that the citizens of a given ruling group would not infrequently challenge, abolish, or abandon the state if the rulers overreached. The sudden disappearance of a script that was used for the purposes of tracking ownership and accounts would fit with this view, especially in light of even more modern reactions to attempts by the state to codify relationships for, eg, tax purposes, or just generally for control.

We may never truly know when writing was invented.

There's a stele that was discovered in 1986 [1] in Veracruz. You could be forgiven if you think that writing is Maya. But it is not. It some other language. A couple other small fragments like it have been found, but the stele is basically an hapax. It is the only example.

And from the one example, we can see that it a system overflowingly glorious in its maturity and complexity. The scribes belonged to a culture that had been writing for a very long time. That is the refinement of millennia.

There are dates carved on La Mojorra 1; if they are in the same Long Count calendar the Maya used, then the stele appears to be talking about something that happened in the 140s and 150s AD.

The obvious relationship between the Mesoamerican writing systems might be somewhat analogous to the Cyrillic and Latin alphabets, or Chinese and Japanese writing. One was adapted to write the other. Or they both evolved out of a common ancestral system. How far back might that have been?

[1] https://commons.wikimedia.org/wiki/File:La_Mojarra_Stela_1_S...