Yes, when there’s a causation link between things there’s also a correlation between them. But correlation does not imply causation means the link doesn’t go the other way. It’s like, every dog is an animal, but not every animal is a dog.

Correlations might be useful to figure out common causes, for example the correlation between student height and reading skills, could mean taller people are more educated, or, more likely, that your students are young enough that age is an important factor at play.

And finally, correlation might be just a fluke of chance, for example the amount of automotive recalls related to AirBags correlates almost perfectly with the popularity of the first name Killian: https://www.tylervigen.com/spurious/correlation/2599_popularity-of-the-first-name-killian_correlates-with_automotive-recalls-for-issues-with-the-air-bags that site has other similar examples.

So yeah, correlation might be important, but they might be nothing at all, so don’t just assume that a correlation implies causation.