Alcohol is not at issue because neither of us propose to change its legal status. I urge you to review the medical evidence as to the considerable harm of marijuana.
Your conclusion doesn't follow from your premise. I propose that alcohol and marijuana each be legal because their bans are comparably harmful, as are the substances themselves: alcohol is more addictive than marijuana, more violence-increasing, and the only one of the two that can lead to fatal overdose. You propose that alchol remain legal and marijuana illegal based on your unsupported assertion that this disparity is based on mankind's "experience and considered judgement".
I urge you to review the medical evidence as to the considerable harm of marijuana.
To repeat points you never addressed: A serious argument for marijuana remaining illegal and alcohol legal is required not only to establish that marijuana is harmful - which, I remind you again, nobody here has disputed - but that its harms exceed those of alcohol. Surely you've seen the ill effects of alcohol?
"Alcohol use disorder (AUD) is the most common co-occurring disorder in people with schizophrenia." - https://pubs.niaaa.nih.gov/publications/arh26-2/99-102.pdf