"Is a shareholder a:
Secured creditor?
Unsecured creditor?
Or just a stakeholder?"
Only a "stakeholder"...and the one at the very bottom of the pile of "stakeholders". All creditors, debt holders, equity holders, employees, taxing authorities, etc. are technically "stakeholders".
But they are not treated equally in a bankruptcy/insolvency/receivership/liquidation etc.
"Harsh reality is always better than false hope"