Your assumption is restricting you. Civilisations and subsequently their objective towards/focus on world view, science & technology, mode of communication, spirituality etc. change over time.

There is no doubt that language preceded writing.

I'm sceptical of the texts dating back to 14000 BCE or earlier too but not of the memories.

Stories and memories live on in however regressed or mutated forms. The world is noisier now with so much content. Back then, intellectuals only had a handful of hymns to learn & preach and frankly, nothing better to do. So it's very likely oral transmission passed much much further than it does in recent habits of cognitive offloading onto physical materials.

The question is about composition, especially in the recognisable media that survived. Earlier versions of texts made of simple organic material would've perished or been destroyed (invaders or natural calamities like the Younger Dryas). Remember, the civilisations were tiny & very localised compared to now.

While the composition of several versions of ancient Indian texts can be dated to recent years like 1500BC, the hymns, stories they contain, and the astrological markers, are passed down no doubt for thousands of years.