Aylin's maybe not a literal daughter. An Aasimar is descended from a celestial, not a god - that'd make her something more.
Nah, she's probably a descendent of one of Selune's angels and calls Selune 'mother' figuratively, although it comes across like she's drunk the koolaid and actually believes she's her mum. I mean, once you start referring to yourself in 3rd person, your ego is controlling you.
Though if Selune were the actual mother, she'd be a pretty terrible one leaving her daughter in such a state for so long.
(And shouldn't druids have a big issue with her running around Faerun? She's clearly outside the natural order. Maybe Kethric was actually in his right mind to object to his daughter's union.)
As for Jesus posing, I've seen plenty of Catholic depictions in my time. BG3 leans heavily into church imagery with Aylin and Withers. Sorry, but it comes across as cliche.
