Haven't read the LN, so nobody confirm or deny this, but my bet is that Cid/Minoru actually did discover magic before getting isekai'd, and he's the cause of what's become of the world.
Same. My theory is he actualy had magic, or perhaps is magic himself. Hell, it seems he has the capacity to completely rewrite history by just saying some bullshit outloud and neither he nor anyone around him realizes the entire world and its values were rewritten with each word he speaks. Or in other words, CID is the author of both worlds.
But similar to haruhi, he is oblivious to this fact. And, on earth, his own belief that magic didn't exist there was what stopped it from actually existing. It wasn't until he bashed his head against a tree and lost enough blood to start loosing reasoning that he was able to convince himself that magic did exist and ran to it.... Yes, it exist, just like in a manga! And he started chanting "magic" aloud as he truck-kuned himself, creating an entire new world with magic for him to live in in the process.
Now, that isn't my head canon by any means nor do I want the author to go in that direction (I firmly believe it is pretty well established by now that any bullshit cid says aloud is true whether he believes it or not. However, if it was true prior to him saying it is still up for debate). But by god I want that truck to be stationary! It fits in with the making fun of the troupe troupe so well!
Longer version: One of her father's company's trucks parked outside her window in their mansion surrounded by woods. While gazing out the window as some new furniture gets unloaded suddenly a buck naked Cid with blood running down his face comes dashing out full speed from the woods and rams straight into the truck causing a massive powerful, and bloody explosion! She panics and runs out to help but freezes. Not because the body was no where in sight, nor because of the frightfully bloody sceen in front of her. But because she discovers what must have been the reason the poor buff simpleton who couldn't remember her name was running from fast enough to have caused this mess. A terrifying bloodthirsty beast!
cut scene But seriously.... Please. Stationary truck! It fits perfectly with the whole making fun of the troupe troupe of this manga!
Also, when did he learn to compress his muscles in the original world? Was that mentioned somewhere? It shows the compression in chap1, but also shows that he didn't always do it or know how to or know he needed to to be an eminence in the shadows.
And as a followup of what I have already written, I kinda wonder if he has bulshitted parts of his own past life into existence as well.