It's interesting about boys, I feel like there are a few different things going on here.
Whilst I can think of boys in fiction that are less of the stereotypical sporty adventuring type and may have personalities that we might perceive as quieter, bookish, kind, I'm not sure they read particularly as stereotypically feminine. I'm wondering if that's because with man as default human they have always had more of an expansive range of acceptable personalities. Whereas a girl expressing sportiness, competitiveness, and at some points in history even intellect etc is seen as wanting to be like a boy/man. What areas are really left to be perceived as wanting to be a girl? Even nurturing younger kids is seen as a leadership/paternal role for boys whereas in a girl it would be perceived as more motherly. Thinking here of Julian taking care of Anne.
There's definitely long been a sort of gentlemanly idea of being a man that is more intellectual or artistic, physically restrained, socially adept. Class playing a role here.
Pip from Great Expectations, Laurie from Little Women. We wouldn't describe them as girlish really but surely sexism forcing women to be judged as acting unnaturally for having a temper, or wanting a writing career or caring more about her family than her beautiful hair are the only reasons we think of Jo March as being boyish.
If we are going to be more strict about what being perceived as feminine would entail then I suppose Colin from The Secret Garden is perceived as weak and emotional with indoor pursuits and may fit that bill, largely because he is or has been perceived as in ill health and in an odd way both spoiled and neglected.
Dicken is more outdoorsy, but he's quiet and intune with animals which if he were a girl would be perceived as kind and nurturing and seen as feminine but again we don't really think of it as not being a suitable interest or character for a boy anyway.
Just thoughts anyway that the older idea of what it meant to be man of a certain class would perhaps be thought of as female stereotypes now but wouldn't have at the time because men held almost all the cards. I have enjoyed all the little trips down memory lane! Currently reading the Famous Five to my kids.