Does Hong Jun really exist in the Taoist myth system?

No, folk beliefs, especially Luo religion, may be said to have (fatherless). Please search for Luojiao yourself.

However, it has also been verified that Hong Jun, the founder, refers to the sage of Hongyuan period and the founder of Hongyuan, one of Laozi's eighty-one. I doubt this statement, but I basically agree.

There is also a saying that the ancestor Hong Jun evolved from Mongolian mythology. This is not clear, but I have only read relevant articles.