My understanding is that the mass is intended to be a recreation or commemoration of that event. So why is speaking it in Latin important?

In the early centuries of Christianity, as it spread geographically, there developed distinct rites of worship that solidified and then were handed down to the present, retaining strong links to the spoken-written languages used to express them originally.

https://en.wikipedia.org/wiki/Catholic_particular_churches_a...

Oversimplifying greatly, but in and from Western Europe we have the Latin Rite, and in/from the East we have the Byzantine (Greek) Rite. There are others, not of less importance, see the link above.

There’s quite a lot of history involved in all this. But in Western Christianity it was Latin that became predominant for public worship and knowledge transmission.