The key here is "prehistory". As in, before written records. Venus figurines are a fascinating Paleolithic artifact class, but without written records, all we have are archaeological interpretations. Because all there is to go on when trying to interpret the Venus figurines in the form, composition, and context of the artifacts, many narratives and interpretations can be created that cannot be disproven at this time.

My primary knowledge of a technically prehistoric society is the Iroquois culture of the Northeastern United States, centered in modern day New York State. We can only make educated guesses about what their culture was like pre-Contact because interactions with European traders, missionaries, soldiers, and eventually settlers unavoidably altered their culture.

With these caveats, the portrait of prehistoric Iroquoian culture is a Matrilineal, Matrilocal society in which ultimate political power still lies in the hands of males. "Patriarchal" and "Matriarchal" aren't terms commonly used in anthropology, because they are too broad.

Matrilineal means group membership is derived through the mother's family line.

Matrilocal means that men move to join their wives' families.

Despite the societal influence and freedom of women in this type of society (women were free to divorce their husbands at will, for example), ultimate political power still remained in the hands of men. Only men could be a Chief (political leader) or a Sachem (military leader).

While no cultural structure would be universal in pre-history, I would postulate that complex societies with a blending of Matrilocal/Matrilineal structure and male-dominated political power would be more common than they are now. This is pure speculation.

I think it is important to point out your teacher's fallacy in assuming a one-world universal culture existed in prehistory. Your teacher is definitely mapping her own beliefs onto the fairly empty canvas of anthropological knowledge of prehistoric societies. Our picture of prehistoric societies is largely empty because there isn't enough evidence of non-physical culture elements like religion and society structure to draw strong conclusions.

Sources on Iroquoian Culture:

League of the Hodenosaunee by William Henry Morgan

Death and Rebirth of the Seneca by Anthony Wallace

A Narrative of the Life of Mrs. Mary Jemison by James E. Seaver

Questions about prehistoric topics might do better in /r/askanthropology.

A lot of these ideas come from the work of Robert Graves, a poet who also wrote historical novels often based in classical times. He's best known for his novel I, Claudius, which is a pseudo-autobiography of the Roman emperor. He did a lot of research into mythology and anthropology, and his literary works have been highly acclaimed (I, Claudius is considered one of the hundred best novels of the 20th Century by both the Modern Library and Time Magazine).

But the non-fiction works he published were never really part of mainstream academia. Specifically, Graves wrote Greek Myths in 1955, which presented stories from Greek mythology along with his own interpretations of them, based on archaeological findings and comparison of similar myths from other ancient civilizations like Sumeria, Egypt, Crete, etc. He also wrote The White Goddess in 1948, which focused on goddess worship and similarities between different cultures, based on myths and poetry. Both of these works talk a lot about theorized matriarchal societies of the past.

These works are interesting to read, but are more creative than scientific, hence why they're not considered "factual." One might compare them to Joseph Campbell's The Hero with a Thousand Faces, published in 1949, which was about archetypes in myths and structures of myths, like the hero and the hero's journey. These books are highly influenced by literary criticism (such as finding similarities in story motifs and characters), and by the work of Carl Jung, the psychologist who popularized the theories of universal archetypes and the collective unconscious—theories that are also not very scientific.

Even though these ideas aren't widely accepted by academia, they still have been highly influential, especially in popular media, because there's a spiritual element to them that goes beyond anything that can be proven.

That's not to say these examinations of ancient myths and artifacts are without merit. Historically, archaeologists and paleontologists, especially the early ones, had been highly-educated European males, who had their own biases when examining artifacts or ancient myths.

Like with the ancient "Venus of Willendorf" figurine, it was first described in the early 20th Century as a fertility fetish, assumed to be pornographic. The term "pornography" comes with a lot of 20th Century baggage, though. Even the term "Venus" is referring to a promiscuous Roman goddess, which seems inappropriate for something 30,000 years old. We can only make assumptions about what the sexual norms and the religious practices were for these prehistoric peoples, and in more recent times other non-male perspectives have joined in the conversation about what these type of figurines could mean, like Catherine McCoid who hypothesized that they may have been created as self-portraits by pregnant women.

I wouldn't say these re-examinations are conspiracy theory, because that's disparaging and the new perspectives aren't necessarily coming from a place of ignorance, even the perspectives coming from non-anthropologists like Graves. Yes, much of it is speculation, especially when we're dealing with prehistoric times, but knowledge starts with speculation.

Such speculation is also a hallmark of Humanities classes, where it's more about discussing human arts and culture as a way to stimulate critical thinking, as opposed to a natural sciences classes such as anthropology where you would talk more about things backed by empirical evidence. So I'm not surprised that more philosophical theories are coming up in your Humanities class. I would encourage you to discuss your thoughts and findings in the class, because IMHO good discourse makes a good Humanities class. (Think of the Socratic method.)