I wonder if I'll be let go if I just let these all go back return to sender -_-
Property tax records are searchable by owner's name in most jurisdictions. They may have used that and selected the wrong address.
I recently had a similar situation. I purchased something online (not a shop). I didn't know they would ship FedEx. Like you I only use a post office box. FedEx somehow delivered it to my house. They could not have found my address via county records because my residence is hidden due to a bill that was passed protecting those that work in law enforcement. Yet they tracked me down. Privacy is a thing of the past.
I intersecpt the package and have it held at the fed ex office or other nearby place they will deliver.
As soon as I get a notice that the package is in transit I say I will pick up at the office. That way I dont need to be at home to sign