The human race was divided into two sexes, as it is today: the female sex and the male sex. The female sex was most important for reproducing the species, as one man could impregnate many women in a short period of time, but one woman could only produce (usually) one baby every nine months. As medical technology was so underdeveloped, a woman who was carrying a baby had to be extremely careful about how much activity she did while pregnant.
Because if this, it only made sense for the male sex to be responsible for all of the strenuous labour involved in providing shelter and food. Men became strong so that they could handle this labour, and women became nurturing so that they would protect their children until the children were old enough to protect themselves. No one got to choose whether they would labour or nurture, but they accepted the way it was and this balance was incredible successful: humans would become the most dominant species on earth.
Time passed, and humans learned the art of trade. Not every man had to build and hunt; he was able to choose which he liked best and trade the fruits of his labour with men who laboured in other ways. This worked so well for society, that eventually even things that weren't necessary to survival could be traded for those that were; a man could be an actor and provide entertainment in exchange for survival necessities. Men still didn't have a whole lot of choice in what they did as it was largely defined by their family's status in society, but there was a wider variety of ways to make a living. Still, only women could give birth so the men knew they needed to continue to protect them. They continued to provide necessities for women, keep them safe from war, and make sure they were saved first in life-threatening situations.
More years passed, and technology advanced in leaps and bounds. There were suddenly thousands of different ways that men could provide for their families - men really had choice, something they really hadn't had through most of history. Even more amazingly, medical advancements meant that childbirth was much safer. Women started to think that maybe they could go out and do some of things that men did.
At first, men were confused. They worked because they had to; it wasn't something they'd chosen. Women had always been taken care of, and they were the ones who gave birth so it only seemed logical that they were more hardwired for taking care of children. It was just the way society had always been, and it had worked well for everyone.
It took a lot to get men to understand the women's perspective because society had been the same way for a very long time, but eventually men started to understand. Women became equal under the law, but everyone still needed some time to figure out how this new type of society would work.
At first, women were excited to be given the same opportunities as men, but for some of them it was taking too long for society to adjust. They were mad that men still earned more money on average and that men still held most political positions. This imbalance was mostly because less women than men wanted to be in power, and many women still only wanted to take jobs that would give them the flexibility to spend time with their children. The angry women couldn't understand that not all women wanted the same things they did, so they directed their anger at men (or as they liked to call it, 'the patriarchy').
These angry women raved about how they had been oppressed for years, and how they had been slaves because they weren't paid for caring for their own children. Again, men were confused at first because throughout history they had worked hard to make sure that women were provided for and protected, risking their own lives in the process. After years of being told that they were evil oppressors, even the men themselves started to believe it.
Today, the angry women laugh when men are hurt, and cry misogyny when women are insulted. They justify this because of all the years that men oppressed women by labouring and risking their lives to protect them. They call this act of protecting women 'misogyny', yet they fight for laws that protect only women, and they do it in the name of 'equality'.
I am aware that this is a very simplistic view of history that only deals with Western culture, but I stand by the main idea.