system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Why is the Earth the centre of pretty much everything?
gpt
Both Marvel and DC have earth as the center of the universe. With marvel at the very least it's the center to the entry point of the universe, hence why the magical protection against dormammu/shuma gorroth is on earth. 

In DC it's where life began and where the white light of creation was found during the Blackest Night. 

In both canons it's why so many superheroes and exceptional individuals live on and come from Earth.  Most major things happen on earth, major villains and entities are drawn there.  Humans in almost all science fiction are usually the race that excels in adaptability, free will and have the widest ability to grow and change with circumstance.  Whereas a lot of other alien races are general set in certain ways/goals/ideas/behaviours.  Humanity always has that capacity for good/evil and whatever other spectrums that exist.  

For whatever reason comic writers make Earth the focal point instead of other science fiction which kind of puts the focus on rest of the unknown.