Not stupid at all! It’s one I often wonder about – did the creators of the show realize they’d built a gaping plot hole into its premise, right from the pilot? And more to the point, did it even matter when literally nobody ever noticed while the show was on the air? But there is an answer, thanks to the AllSpark Almanacs – whether it was a bit of info that came from the showrunners, or an idea created by the Almanac writers to explain the goof I don’t know, but the books established that Vector Sigma also exists in the Animated universe, and was used to bring life to the protoforms that became the post-war generation.