Freemen make bad corporations
Many of the laws and bylaws that give investors power over a corporation do not apply to human corporations. For example, investors generally do not have the power to make executive decisions, but they do have the power to appoint executives to run the business on their behalf, and to set the salary of those executives. Choosing appointees is a matter of trust because EOs have a lot of authority to screw over the investors if they so choose. Part of why publicly traded corporations are run by a Board of Directors (BOD) instead of individuals is to specifically ensure the trustworthiness of the leadership. So, if you do not like the choices an EO is making, you just replace them, but you can not do that with an incorporated human. Not being able to fire the executive officer or appoint a BOD significantly limits the authority of an investor over the incorporated person.
At most an investor could threaten the incorporated person's salary if they make unfavorable choices, but if you raise your dividends above the standard interest rate, then the person could just do a "leveraged buyout" (LBO). IE: as the sole executive officer, the person has unilateral authority to take out a loan and buy a 51% share hold over himself. In this case, he could change any bylaws he wants and set his own salary to 100% of profits and leave the other shareholders with nothing of value. For the individual, this replaces the shareholding with a fixed interest loan that they can eventually pay off which would be much more manageable. Banks knowing that this could be a major source of revenue would heavily advertise their LBO services the same way that they advertise refinancing loans now.
The only way I could see incorporated humans working in any general since is to make the dividends much smaller than normal corporate dividends (which makes them less worth trading), or to make parents the de facto 100% shareholders over their children. Society could see this as an alternative method to Social Security. It would strengthen the incentive for parents to not be abusive pricks because their chances of seeing a retirement income out of their kids will be based on if their kids liking them enough to not do an LBO at the first possible opportunity. Parents in severe economic circumstances could sell their rights to a child's income to another person, but probably at some highly devalued rate because of the risk and low payout compared to other investments.
This would work much "better" with slaves
In order to make trading in human corporations a safe investment, you have to have a legal system that takes away many of their rights that exist for both humans and corporations in a modern context. First and foremost, you need to take away a person's right to make financial decisions for himself to prevent LBOs, Devaluations, and other things that are normally only manageable (to a degree) via a system of distributed trust and replaceable management... and if a person can not make their own choices about how they manage their resources, then you have people who are by every reasonable definition slaves to their investors. Now investors can take whatever % in dividends they want, and force their investments to do whatever they want under the threat of increasing dividends, and the human corporation has no authority to force an equitable relationship with the investor.
But just because this is the law does not mean that people will comply to such abuses. If they can't make an honest living, they will just switch their activities to illegal, untraceable income. It's better to be an undocumented handiman, a drug dealer, or a prostitute than to be a licensed doctor who can't afford to eat. So, incorporating humans would incentivize a major surge in crime rates and civil unrest. This means that the legal system also needs a way of keeping investment dodgers from pursuing alternative incomes. But an imprisoned investment can't work which mean you need to build labor camps where you can force investments to make a traceable income for their investors and/or you will need to rely on violence to harshly punish investment dodgers for not following the rules. This will inevitably lead to a system of people living in cages under armed guard to make sure that they honor their investors... at which point this just becomes a slight variation on chattel slavery. But, instead of plantationers owning their slaves, they are just the investor appointed EOs for the slaves.
If you want to make humans as corporation slaves in the most humane way possible, see this Related Post.