Lethargic Man (anag.)

Jeremy Gordon once talked about it. It was actually meant for teenagers but I found it interesting as well. I had not so much text in front of me. He explained that the prophets have the idea that we eat the sea-monsters when the messianic time arrived. The text you provide here does not see anything about messianic time nor that the people in the wilderness are necessarily Jewish. I think you are right. Those sources seem not to be Jewish sources.