Genesis 38:8-10: 'So Judah told Onan, “Go and sleep with your brother’s widow; it’s the duty of a brother-in-law to keep your brother’s line alive.” But Onan knew that the child wouldn’t be his, so whenever he slept with his brother’s widow he spilled his semen on the ground so he wouldn’t produce a child for his brother.'

So this demonstrates a pretty sophisticated understanding of sex and parentage from a long time ago.

Incidentally, this verse is often misinterpreted to be about masturbation, when it is about coitus interruptus. The Bible actually has no verses prohibiting masturbation, and a single reference to wet dreams, the "punishment" for which is to clean yourself up.

Depends on what level of detail you want to get into. It was in around ~1992 that it was found that the egg actually attracts sperm, rather than passively sitting there.

I'm not sure when exactly this changed, but I know that during the middle ages in Europe, it was believed that the sex of a child was determined by how much "heat" was present at conception, and that men and women had the same genitals, but internal vs. external. Basically, the belief was that everyone was supposed to be a man, but if there wasn't enough heat during conception, the penis and testes wouldn't drop from inside the baby's body, and would remain internal as a vagina, creating a woman rather than a man. People tried all sorts of stuff to make conception as hot as possible (perhaps helping create the term "hot sex"?) in order to have male children. Also, it was thought that because there was less heat present at conception, women were "colder" throughout their lives, and therefore more "prone to sin". Obviously, we then started dissecting human bodies and studying things other than the bible to inform us about sex, and we realized that no, women are not just men who didn't turn out right. During the Renaissance, people started to investigate the human body a bit more, so that may have been when this belief died out.

TLDR: In the middle ages, people thought women were men who weren't conceived properly.

edit - look for work by Steven Stowell if you want to know more about this kind of stuff. He's a prof at my university who specializes in sex and gender in medieval and Renaissance art.

There is an interesting introduction to the Greek Myths by Robert Graves, in which he attempts an anthropological interpretation of the myths. In essence, he says that in bronze age tribes, women were considered more important than men because of their role in creating new life. The head of a tribe would be a woman, a sacred queen. Men's role in conception was not understood because of the time gap between sex and appearance of pregnancy, and hence they were given menial roles in the tribe (hunting and gathering - much lulz when I read this!) Gradually, as it became clearer that sex was a necessary act for pregnancy, men became more important in the tribe; the sacrifice of a male victim at the height of winter was replaced with a proxy victim (an animal) and the male was appointed a temporary co-regent. Over time, this led to a religious clash of roles, and eventual patriachy. All this is, according to Graves, represented in the feud between Zeus and Hera in the myths. It's an interesting read (the introduction) and I summarise it here as a reader of the introduction, not an expert in any way. However, it does seem relevant to your question.

Remember reading an article in History, one of National Geographic about this. Pretty much up to the 18th century most scholars believed the male were the most important person involved. He sprayed the child into the woman, and she was just the carrier. The greeks believed it, and prominent academic figures in the renaissance believed it. So it's safe to say they didn't really know what went on.

The answers so far address the male portion of conception. What about the female portion? St Augustine discusses female fertility cycles in the early 300s, and certainly every farmer knew about animal fertility cycles. Many women feel when they ovulate, and that feeling is connected to fertility. But when did we figure out that a tiny egg contained important stuff for conception?