You're basically arguing that if a company pays a CEO what good CEOs get paid then they could pay their workers more instead. But that doesn't work, because you have to pay a CEO what good CEOs get paid if you want a good CEO.

The shareholders can't just hire a random janitor at a janitor's salary to be the CEO and expect to not lose more money to unqualified decisionmaking than they would've had to pay a real CEO.

Likewise, they can't just make zero profits forever, because otherwise they couldn't raise capital. If they're a new company they need that investment in order to buy land and build the factory etc. If they're an existing company then they still need that, or the shareholders would sell their shares and the only buyer would be a corporate raider who wants to tear down the factory for scrap and sell the land to a condo developer.

Salaries and profits are relative to the market average. Unless the company is paying its executives more than the average company, or making more profits than the average company, they don't really have a surplus they can give to the workers without becoming uncompetitive.