I think you’re talking to some people who, in bad faith, are demanding “proof” when they need to learn how to acknowledge “evidence.” Someone with a fixed attitude will keep moving goalposts and cherry picking outliers until the cows come home, and you need to be able to say: your bias is overwhelming in the gymnastics you perform to avoid the clear evidence. The process of science most often doesn’t produce black and white results. Anti-vaxxers are gonna anti-vax and you can’t “persuade” them.

That said, if you can’t provide 7-8 stories with female protagonists, which are very popular, you’re not even trying. His Dark Materials. Moana. The Fault in Our Stars. The Fablehaven series. Frozen. The Force Awakens. Silo. Mulan. Legend of Korra and the Kyoshi novels. The Sarah Connor Chronicles. Star Trek Voyager. Anne of Green Gables. Watchmen (2019 series). Jane Eyre. Pippi Longstocking. Little House on the Prairie. …

If you’re really talking to someone who says “there are no stories with…” then here’s enough to easily force them to change their position to “there are far less stories with…” and at that point they would in fact be correct.