Earlier quoted context omitted.
No, they aren't. Corporations don't magically do things that the group of actors working together don't do.
They literally do. Plenty of legal and regulatory constructs apply only to corporations. Limited liability is a thing that is available by forming a corporation, as is carrying out an SEC filing and selling stock. A corporation can also survive, as a legal construct, the deaths of all founding members.
Remove those features, and things would change a lot, but you'd still have 'corporations' of a kind.
Corporations are also not primarily profit driven - the owners may are - but corporations themselves 'do things' which will result in a lot of externalities and surpluses generated elsewhere, only some of the profits may come back to the shareholders.
Corporations are:
Shareholders, Debtors, Buyers, Suppliers, Executives, Employees.
Shareholders may very well be the smallest beneficiaries of an endeavour. They have certain rights, but other groups have rights as well: lenders have first rights to the assets, and so do other creditors such as suppliers. Employees have legal rights including collective bargaining.
Buyers may have incredible power over companies such that they suck out all of the profits (see: selling to Apple).
Debtors have all of the power during restructring.
Many companies exist at the whim of the employees - like big Auto, who pay super high wages and benefits relative to the job. Possibly government employees as well.
Some Execs, by virtue of a weak or allied Board, have all the power and suck out vast profits that would otherwise go to investors.