Shadow couldve been created after the ancient Echidnas' Super Sonic prophecy, which would explain his spine shape and being built to handle Chaos energy. So he was modeled after Sonic before Sonic was even born, which is why they're so similar.

It’s crazy how Gerald rebotnik created shadow to be the ultimate life form just for it to be born naturally

I believe that when Shadow tells Sonic that he may be the Ulitmate Lifeform, he's referring to the fact that Shadow is based off of Super Sonic. (This is why he only mentions it when they are in their Super-Forms.)

I once had an idea that Sonic And Shadow are actually two halves of what once was the true ultimate life form. And the Mephiles and Iblis thing was supposed to mirror this. Probably not true, but just an idea.

In Sonic Unleashed, there’s another example of the Chaos Factor: after the werehog is launched into space, he’s save by s green orb that breaks his fall. Now you say that’s Chip/Light Gaia, but that’s never confirmed in the game.

In the movie, it was hinted at the Sonic's speed is some manifestation of Chaos Control. It explains why the Echidna kept trying to hunt him down as a child and why a single quill was able to power Robotnik's mechs.

My theory is somewhat similar.

I think the reason is that he was connected to the chaos force is a good person. If you think about it, we have seen Sonic perform many Noble acts of kindness. Even though this isn't cannon, Sonic possibly could've ran away from Galems beams, but instead he stop to grab picachu or at least tried to. Mind you out everyone else in that scene, Sonic was the only one who looked back to try and save someone. Link didn't tryed save Zelda, Pit and Dark Pit didn't try to save Palutena. Kirby was over here just just flying through the sky, Snake tryed to hide in box and the list goes on and on. The only other person that I saw try to help was Bowser with the Pokemon trainer and Shulk trying to warn everyone of what was coming. So yeah, me personally, I think that Sonic is just a kind person and that he is made using the chaos force which your theory. Plus Sonic has resisted min so control before in Sonic and the dark brotherhood.

Great theory I have always thought Sonic was the “chosen one” because of just how the stories play out so thank you for confirming my theory as well

Your theory is not silly, everything you said is very interresting and possible :)

I'd say Sonic is indeed the ultimate life form

“The fates will convene to ensure your victory” is us haha. As no matter how powerful they get we keep retrying until they lose!!

If I’m gonna be completely honest, I’m kind of digging it.