We seem to over complicate things as humans and don’t look at things the way they are.
At the Luxor Temple in Egypt, Ancient text displays a sperm cell coming out of the pharaohs erect penis: https://imgur.com/kSB75XW
Focus here: https://imgur.com/a/iuA6ecn
Now, deduce what you see? Don’t complicate it, because the truth is in front of you.
They knew how a Sperm Cell looks like because they saw it.
Pictures removed?
https://pasteboard.co/JGtDyss.jpg [First] https://pasteboard.co/JGtDJhp.jpg [Second]