First, I don't believe in heaven.
However, working within the construct of the bible, I see no mention of any Law, rule or command that prohibits drug use per se. Maybe stealing or sucking cock or assaulting people is a sin, but that is a separate thing from drug use, you can be sober and do those things, you can be high and not do them. Hence they are indeed not implied simply by drug use it self.
Finally, just because pot or shrooms are natural is not a sufficient argument to claim they are 'good'. Many natural things are VERY VERY bad. Botulinum toxin is 100% natural. It is also the MOST toxic substance know. One type of it has an LD50 of about 30 nanograms.
Also "hard" drugs can be natural too...you know MORPHINE via opium. You can just smoke the opium like pot, 100% natural! So does Cathinone [which a reasonably strong stimulant that is the ketone of amphetamine] Your argument is an appeal to nature, which is usually a fallacy, and in this case, can be shown that nature makes the most powerful poison, and one of the most addictive drugs know. So no, pot and shrooms and DMT don't get a special place because they are found in plants.