Doing a bit more research here's some extra things to ponder -

DMT is [according to Dennis McKenna] only 2 synthesis steps away from the amino acid Tryptophan.

So with this in mind [and in perspective to redundancy / co-opting of similar molecules for different aspects of cell biochemistry]

It is perhaps not unusual that DMT as a basic/simple chemical [in the sense that it is more likely to be produced by multiple organisms than a more complex molecule] it would be in many organisms, and also with many potential uses.

So yeah,
maybe it's just a consequence of it's basic structure as a variant on an even more basic building block chemical [tryptophan].

A little less exciting perhaps than other stories about it, but still handy that Jurema produces it in such high amounts and it affects the structure of our mind so amazingly.