Seems very complex. Do any of them need flying machines to get around?
Depends upon the version being studied. There are some wingless angels, and had bodies at one time, so perhaps so.
There seems to be a common system of spiritual capacity in these creatures, which might not always be similarily accepted within different denominations. Christians well accept God the Holy Spirit regenerates the human spirit upon faith in Him through Christ, but the meaning of the spirit differs considerably amongst believers and nonbelievers.
Even amongst Christian believers, different spiritual gifts are given to different believers, so there is substantial room for confusion even amongst believers on the topic.
IMHO, many UFO testimonials indicate a spiritual involvement.