I used "devise", not "device". This term does not always mean "escogitare" in English. It can be used simply as a synonym for "create" and contains no idea of cunning or shrewdness in this context (i.e. no "astuzia" is present in this usage) It has a particular nuance that does not detract from the idea of create, but reinforces it in this context. This word is appropriate, see examples here:
https://www.academia.edu/20818148/Political_Myth_Mythology_a...and
http://mentalfloss.com/article/83422/14-legends-about-cats-a...Your comment: "create representations of deities" is not very good English usage and as a native English speaker I would not use it.
Also, regarding "A myth" = I think you have misunderstood my usage. "A myth" does not represent "one single myth" here. I am aware that this is regarding many myths, but in English we can use this construction to suggest something that happens on a regular basis. This is a particular style of speaking, and my version means something different than you are suggesting. However, I will try "the mythology".
I hope this is now clear.