I think we have a diverse spiritual world with different "beings" but it's hard to track this is in Bible. We have mention of lying spirits, deaf and dumb spirits, unclean spirits, haughty spirit, familiar spirits and many more. Some may refer to spiritual beings and some to the intent or mindset of a person. Or both
I think satan, the beast, and the false prophet are actual devils/demons and they send out spirits ( spiritual beings ) and this can be loosely referenced in Ephesians 6. This implies devils can assume human form. imo
The people Jesus called " a generation of vipers" were also described as "of your father the devil" and this refers to their nature. They were following the path of deception which was instigated by satan.