How come my homepage doesnt work on iPhone?

It’s because you activated the Mobile Theme option on JetPack. You’ll notice that if you scroll all the way down to the bottom, you’ll see a link that reads View Full Site, and if you tap on it, your full site appears as it should.

So you’ll want to deactivate the Mobile Theme option on JetPack, since the Oxygen theme is already responsive. Click on Jetpack from the WordPress dashboard. Scroll down until you see the box for Mobile Theme. You’ll see two buttons, one labeled Learn More, the other labeled Configure. Click the Learn More button, and you’ll see the Configure button turn into a Deactivate button. Click that button, and your site should now appear normally on mobile devices.