Was Bob a human ever ?

Initially when you watch Twin Peaks you may think that Bob is a spirit/ghost of some serial killer that is possessing people. He looks Native American(representing places where events are happening). He seem to have human name Robert, using letters from his name to put under the fingernails of his victims. Not only Laura, Leland and Sarah saw his appearance, but also Ronette Pulaski, Cooper and Philip Gerard/Mike.

In episode 8 of The Return however we see how he was spawned after nuclear explosion in the form of orb, so we start percepting him as more of an abstract form of evil, rather than a person.

However we also saw Laura in form of orb, the one that Fireman/Giant created, but we clearly know that Laura was a human later.

Does that mean that Bob could indeed have a human form before becoming the inhabiting spirit? And if so - how he was able to become one? Some dugpa sorcery or practices Windom Earle was referencing?

What are your thoughts?