I think that world2ch wasn't the first imageboard ever. There was a Russian Linux-related forum, which had an anonymous posting feature, even with images (in "gallery" section). And it was late 1999. So, technially it can be called a first imageboard.
Proofs:
https://www.linux.org.ru/gallery/archive/1999/11/ (some of the screenshots are uploaded anonymously)
https://www.linux.org.ru/gallery/screenshots/18239 (an example of thread with anonymous posters)
https://www.linux.org.ru/forum/desktop/4564?lastmod=928699200000 (even older example (June 1999), but in the "forum" scetion, without images)
world2ch wasn't ever an imageboard. world2ch is the first anonymous English language chan/bbs modeled in a similar format to 2ch/2chan.
world2ch wasn't ever an first anonymous English language chan/bbs modeled in a similar format to 2ch/2chan. world2ch is the first, penis