From what you have already mentioned, I would add human curiosity. Not everything has a deep psychological or social background. We just like to explain it this way. It's also a learned way of exchanging thoughts and views: to fathom why. Personally, it has so captured me that I have turned it into a profession. But for some time now I have also been agreeing with those who give less importance to the "why" than to the "what do I actually want from life?
I hear a little of Gabor Maté, who has dealt very intensively with the subject of drugs and who, in my opinion, suffers a little too much. Whereby he is certainly a brilliant doctor and information provider. But I think he's long since out of old age, where he still tells his past in such a decorative way. Cannabis is harmless in my eyes, much more harmless than alcohol, for example. Which certainly has something to do with the fact that the latter causes greater damage in my immediate environment and releases aggression. That's why I'm very much in agreement with you: Everyone knows best for himself what can be dangerous for him personally and what not. Not only do the same substances and quantities work differently as you say, but also the daily form, mind, environment and the kind of company and vibration that others produce when you take something.
The best thing you can do is to give sufficient and correct information. With children, it is hoped that their first experiences will take place in the presence of reasonably clear and self-confident people who are there for each other. Whether one has instilled sufficient reservations and caution in one's own child will only become apparent when one has lost control.
When I was younger I was really very curious and I was looking forward to some new experiences. I was never afraid and maybe that's why I was spared a horror trip. Except for one episode, which I found quite frightening, but which I think clearly about afterwards. It didn't hurt me and everyone has a right to try it. You can't really talk to children if you don't have at least one experience that's about the same as what they're going to try. But of course we were also sufficiently informed about very dangerous and quickly addictive drugs. That helped me, I had a great respect for heroin and would never have accepted anything on offer. An enlightening film was enough, I think it was called "Life of Christiane F.".
I had a funny incident when once, after I had taken something, I went to the ladies' toilet, sat down there and consciously wanted to have black thoughts. That didn't work at all, because I had to laugh at myself and this absurd move of mine to produce a horror trip on purpose:). Since I had heard so much about it, I wanted to test myself.
The only thing that remains is to keep enough trust in the child's self-acceptance and self-love. Everything else, mistrust and boundless fear is poison.
Your word-origin definitions are always great fun for me and I therefore thank you for this research and enlightenment as well as inspiration for the answer.
RE: On humans and their choices...