What is the universal meaning of Mary Shelley's Frankenstein?

I am not sure there is a "universal meaning" in Frankenstein; other than maybe you should not have carry guilt wherever you go. When I was mentoring a young man serveral years ago, he was taking a AP cl in literature. One of the books he had to read was Frankenstein. Actually, we both read it. There is a chapter where the "creature" and Dr. Frankenstein are in an ice cave talking to each other. The creature carried most of the conversation. I remember one quote from the chapter wherein the creature told Dr. F. that "wherever you are, I am". Using this quote as a thesis for his paper, we posited the theory that the creature did not exist at all, and that the creature was in fact Dr. Frankenstein's alter ego. The alter ego was brought about because Dr. Frankenstein had tried to play God. Earlier in the book, Dr. Frankenstein does his work with various dead bodies and feels intense guilt about doing this type of work. He managed to have a little success but the results created were abberations of nature and did not exist very long. Just as a side light, there is an obscure theory that Mary Shelly, who was the sister to Percy Shelly, wrote this book to portray her brother as the creature, and Dr. Frankenstein as Lord Byron. Lork Byron took her brother under his wings and they went all over Europe having one after another. Percy died early with an STD and Mary blamed Lord Byron for this because he took an innocent youth and made him into a monster who died a terrible death.