I think you're right that stock trading has enabled a lot of bad and perhaps shouldn't have been allowed. At least on a large scale beyond a single town or county. Paper certificates for money may have been a bad idea too. Even the use of a common currency like gold may have been a net negative. I think a barter system has positives over a common currency in that it requires people to work together and form communities.

Investment as a form of collaboration and results distribution is probably fine. Tho, I would not be opposed to limits on size/scale for companies, individual wealth, pay ratios, etc.

Shorts, options, and other "exotic financial instruments" are worse than gambling because they compel corrupting (withering) behavior.

I think an active, forceful SEC based by a similarly aggressive DOJ, both focused on benefit-to-working-class primarily and market-health (e.g. lack of rent seeking, monopolistic, or monosoponistic behavior) secondarily, would lead toward a better (for global society) market. I think that could be true even if we continued to allow fairly arbitrary contracts that are those "exotic financial instruments", options, and shorts.