You may consider it weird or creepy, but I really like spiders, and I hate the bad rap that D&D and similar games and mythologies have given them.
Especially with Lolth - the biggest, baddest, nastiest evil deity (according to a great many players and GMs) across at least two different settings, countless books in one of those settings, and making half-referenced glances into others. A traitor to an entire race and the mastermind behind an incredibly evil, sadomasochistic, demonic, twisted, perverted society. And what's her thing? Spiders. Spider spies, spider-themed getups, half-spider monsters as servants and punished failed underlings, spidery demons at her command. After five editions of that, or three and a half for those of us who jumped to Pathfinder after 4E came out, it's no wonder most fantasy fans see spiders as creatures of evil. (Well, aside from the general "spiders are icky" thing... which frankly, as many people before me have discussed, is a terrible reason to make something evil. Beauty does not and should not equal goodness and ugliness should not equal evil.)
Which is exactly why I wanted them to be nothing of the sort in Finiens. So almost immediately, when we started working on our custom pantheon, I set out one of my many goals with the setting to be "I want a Lawful Good goddess of spiders". I wanted Finiens to have an Anti-Lolth. Which rather naturally led to the well-known Greek myth of the weaver Arachne and her contest with Athena. Since Athena was associated with owls, it was a very easy stretch to connect our Athene with the harpy goddess Irshya, and from that point the backstory wrote itself: a variant of the Arachne myth where the arrogant weaver who defied the goddess and was punished for her pride was instead the innocent and Athene the guilty party who punished her out of spite and envy for a mortal outdoing her at her own game.
The other part of the Children was that I've always loved spidery races in D&D, particularly aranea and driders. However, with no drow and no Lolth, there was really no place in the setting for the latter, no matter if you spin their creation in 1st-3rd editions' "punishment for failing a divine test" explanation or 4th and 5th editions' "gift of empowerment for particularly pleasing priests" reasoning or even Golarion's "demonic body-warping alchemy that has default effects for each race" workaround due to Lolth's absence. I wanted them, or something like them, in the setting; I just hadn't worked out how to do it yet. And I didn't have any idea at all what to do with aranea, other than knowing I wanted them around and I wanted them to be playable.
Reading around the internet, I stumbled somewhere onto a particularly interesting bit of personal lore someone had posted. In the games of the person in question - whose name, sadly, escapes me - their elves were an alien species that was more spider-like than humanoid. They were born as spiders, then developed the elf shape in adolescence and early adulthood as a form of natural camouflage. From there an elf would become a drow as they continued to develop and age, then reach the full potential of their life at complete maturity when they would become a drider. If I remember correctly (and please inform me if I do not!), the whole elf-drow hostility was an internal sham, meant to keep the true nature of the elf life-cycle a secret from the other races. I really liked this idea and, with some obvious tweaks, promptly stole it for my Araneas.
The creation of Arachne happened a short time later, and the two fit so well into each other that everything just flowed from there.
I really love the lore we've created for the race and the way they've turned out thematically and mechanically. Arachnes are one of only three of our custom races I've personally had the opportunity to play - the others being Naga and Leanaí-Dubh, which will both be expanded on in the future - and playing Siobhan (pictured with her younger sister Roisin, played by Scint/Ladybug) in Faceless's Rise of the Runelords was a ton of fun. The memory of the spider-knight bypassing half the dungeon by walking on the ceiling of a half-submerged cavern and dragging the rest of the party through the water on a threaded raft will live in infamy in our group, I'm certain. I wish we could resume that campaign. Ah well, c'est la vie.
All in all, I think things developed pretty well for the Children of Arachne and their ancestor goddess. They've already seen a great deal of use as both PCs and NPCs, allies and antagonists, historical and modern, and much more at our tables. In fact, I think the only games we've played where no Children have appeared as PCs or NPCs are Scint's old Council of Thieves game and our currently-running Age of Worms campaign, both of which were set in Stormwind, far from Wachara where the spiderfolk originated.