> But why tax corporations at all?

Because otherwise they make great tax dodges.

> All of that money will eventually be income for an actual person (employees, shareholders) who will be taxed on it, most likely at a rate above 24%.

No, it doesn't. The stuff that becomes employee income mostly isn't taxed as corporate income (its a deductible business expense). If it is distribute as dividends, its taxable to the recipient, but certainly that doesn't happen with all after tax corporate profits. Its very common for most investor returns to come as capital gains with the money retained/reinvested in the business.