IT is relatively easy for a Creator Soul (this is a species that predates galaxies which we are a part of) to incarnate as a human being here on earth

 However, you have to have permission of the Galactic Sentience to do this and older Creator souls (billions of years old) when they retire all usually have permission to do this at that point from then on.

How this is accomplished:

I have written before about how a Creator soul of that species which we are also a part of (is sort of like a radio or TV station that can broadcast or communicate across an entire galaxy (especially the Galactic Sentience or Family Leader of this Galaxy is good at this. IT's sort of like having good ears and strong voice so you can call all across a wide field or area as a human being and then be able to hear the response across that long or wide field or across a valley between mountains.

So, because a Creator is usually almost anywhere within a Galaxy or all places within a galaxy all or most of the time in the first place it is easy for them to broadcast into a human body on earth and become a human being here. But, mostly retired Creators (at least at this point) do this. 

Also, Earth is a retirement community for retired Galactic Creator souls as well.

The demands of being an earth born human tends to make life interesting enough for a Creator Soul to stay alive longer and longer and longer while living in one or more human bodies here on earth or on other planets as well in our galaxy.