I've been doing some considerable research and experimentation with the Goetia (Lesser Key Of Solomon).
There are, many views on exactly what the Goetic Demons are. Some say they are actually demons in the traditional Judeo-Christian sense of the word. Others, that they are mainly pagan Gods, gone, but not forgotten that got labelled as "demons" by the monotheistic religions that displaced them. Another, interesting idea I will explore, if only briefly in my next book, is the idea that they are "Jinn", creatures that were created by God from smokeless fire (rather than fallen angels), this is an Islamic idea that can be found in the Koran, where Solomon is seen to cause these Jinn to work for him.
Here is some interesting reading, based around this idea:
The demons of the Goetia aren’t what you think
Don't be scared!
The Infernal Toxic One