IANAL

Physical property can not be copied, so if physical property is taken, then the physical property can be stolen.

Digital property can be copied, so if it's copied, you no longer have a single instance of said property, you now have the original property and the copied property.

Can we actually say with absolute affirmation that it is theft if a good is copied, regardless of what the law states? Is it moral or immoral to copy a good? Can we equate it to actual physical theft of property and state that it has the same level of immorality that allegedly causes harm?

This is where Intellectual Property and Copyright play a role. Copyright is a License granted to use a service or medium of an original work. Anything that can be duplicated, copied, or otherwise easily reproduced without affecting physical removal isn't necessarily theft. The harm that's typically claimed is that of affected income.

If I file for a trademark for a Logo, Character, or otherwise recognizable branding, then it "can be said" that "I own said 'property'". At this point, it becomes trademarked intellectual property. That's how and why someone that "owns an IP for a character" can sue someone else for use of said "intellectual property".

Typically, when someone wants to access said "property", they need to "pay to gain access" or "gain permission for use", e.g. a License.

I can only go off of what I've read from official sources. Regardless, I think it's immoral to own an idea. It would be more beneficial to share with society than to hoard ideas that are essentially copyable and easily reproducible mediums of information. It doesn't cost anything to copy, reproduce, and redistribute the copyable good.

I think a solid middle ground that would benefit both individuals and society as a whole would be to enforce attribution, but not property rights upon non-physical goods or services, e.g. only require accreditation for critical services like health care, insurance, banking, electrical, etc.

For example, Owning the intellectual property for, let's say, a camera for over 75 years and requiring anyone that produces a camera to pay royalties is absurd. Anyone should be able to produce and distribute a camera. Owning the idea for how to create a camera, allowing that to affect anyone that can, and does, produce a camera is immoral, even if it is lawful.

The nuances of how this is considered is open to debate.