If happy minds and healthy bodies require marijuana-like chemicals, which you say is Divine Providence at work, then surely this will have been stated somewhere in Sacred Scripture or Tradition. Can you point out where in Scripture or Tradition that this is stated?
The prefix "endo" means
internal, within. Thus endocannabinoids are intrinsic to our bodies. (Similarly:
endorphins are our internal form of morphine, with the etymological root
orph from the soothing effects told of in the Greek fable of Orpheus. Other uses of "endo" appear in endoscopic, endoplasmic, endodontic, etc.)
Turning to Scripture, one such citation would be from 1 Corinthians 10:13, "
And God is faithful, who will not suffer you to be tempted above that which you are able: but will make also with temptation issue, that you may be able to bear it."
Therefore, at issue is not so much the chemical structures per se but rather the circuмstances that lead a person to seek out external sources to supplement/replace these chemicals: conditions where the body is either prevented by some illness from producing normal maintenance levels or where those normal levels don't serve to alleviate sufficiently the presenting pain. If that pain has a primarily
physical source, then the discussion turns to THC, etc. If that pain has a primarily
spiritual source, then that's a separate discussion entirely (see: Job).
The crossover cases (whether spiritual pain due to physical pain, or physical pain due to spiritual pain, or worse yet a reciprocal spiral) become a matter of carrying one's cross, or not, as it were. The distinctions matter for clarity of understanding yet can't always be discerned so easily. Sometimes we pray, wait, and leave the rest to God.