Lego to launch first LGBTQ+ set – toy company's designer Matthew Ashton says he was inspired to support the community with rainbow-themed creation

The blue / white / pink are the trans flag colours, and so we finally have some canonically trans Lego minifigs.

The pink, well known to be generally a "female" color

That depends on which culture you're talking about, and even then it can vary over time. E.g. In Western cultures, the very idea of gender colour associations is actually a rather recent development, and funnily enough, was originally the opposite of what it is now. :P

See: Smithsonian Magazine - When Did Girls Start Wearing Pink?

The march toward gender-specific clothes was neither linear nor rapid. Pink and blue arrived, along with other pastels, as colors for babies in the mid-19th century, yet the two colors were not promoted as gender signifiers until just before World War I—and even then, it took time for popular culture to sort things out.

For example, a June 1918 article from the trade publication Earnshaw's Infants' Department said, “The generally accepted rule is pink for the boys, and blue for the girls. The reason is that pink, being a more decided and stronger color, is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl.” Other sources said blue was flattering for blonds, pink for brunettes; or blue was for blue-eyed babies, pink for brown-eyed babies, according to Paoletti.

In 1927, Time magazine printed a chart showing sex-appropriate colors for girls and boys according to leading U.S. stores. In Boston, Filene’s told parents to dress boys in pink. So did Best & Co. in New York City, Halle’s in Cleveland and Marshall Field in Chicago.

Today’s color dictate wasn’t established until the 1940s, as a result of Americans’ preferences as interpreted by manufacturers and retailers. “It could have gone the other way,” Paoletti says.

See also: https://en.wikipedia.org/wiki/Pink#19th_century

In 19th century England, pink ribbons or decorations were often worn by young boys; boys were simply considered small men, and while men in England wore red uniforms, boys wore pink. In fact the clothing for children in the 19th century was almost always white, since, before the invention of chemical dyes, clothing of any color would quickly fade when washed in boiling water. Queen Victoria was painted in 1850 with her seventh child and third son, Prince Arthur, who wore white and pink. In late nineteenth-century France, Impressionist painters working in a pastel color palette sometimes depicted women wearing the color pink, such as Edgar Degas’ image of ballet dancers or Mary Cassatt’s images of women and children.

The US presidential inauguration of Dwight D. Eisenhower in 1953 when Eisenhower's wife Mamie Eisenhower wore a pink dress as her inaugural gown is thought to have been a key turning point to the association of pink as a color associated with girls. Mamie's strong liking of pink led to the public association with pink being a color that "ladylike women wear." The 1957 American musical Funny Face also played a role in cementing the color's association with women.

p.s. For reference: Think Pink! (Funny Face, 1957)