What made you think that you created the Stars, when the stars have existed before you were even born?
Explanation: just incase it's confusing here is it broken down. I'm take inspiration from Greek mythology and other mythology, religion and even dnd to build the foundations of this world. These foundations may not 100% aline/stay true to mlp lore and doctor who lore.
So of course in Doctor who and in our world stars aren't created they are balls of gas, but in that same breath magic doesn't exist and the Doctor will 99% of the time find a logical solution. However ! Magic is real in Equestria and things can just appear out of nowhere and people can travel through time and different realms with magic so the doctor has to accept that in this realm magic does exist and anything is possible.
Star Swirl created time magic and he travelled to Skyros which is described as another destinational realm, at this point in the story he's only travelled to Skyros, he's not played with time magic yet. Of course only very gifted ponies like Star Swirl and Twilight can do this so the are limitations.
As for the origin of the world, Alicorns are like the Olympic gods. They are immortal unless killed, they have great powers that are special to them. Many say after the Trojan war the gods stopped interfering with mortal affairs and left them alone. That's what the alicorns did but instead of a Trojan war the Equestrias are like Eve in the bible and instead of creating hell they just left thus like greek myth and Equestria entered it's dark ages after that.
Then the bit taken from dnd is that of course gods in dnd can just start off as humans that ascended to Godhood, and so this is the same for ponies. Twilight was a pony who leveled up and became a God. Gods in dnd can be killed and overthrown. For example Mystryl died and then came back as Mystra, if you play bg3 Gale a human Wizard can become a God.
I'm using story elements from G5 but mainly G4, this is a fan work and is following it own lore and own world building. So thing are gonna be different from mlp and doctor who. Celestia and Luna raise the sun and the moon the sun and the moon don't orbit the planet the same way, stars are not planet's, some planets are visible yes and look like stars but they are. Stars are balls of gases in real life but instead of being balls of gas they are magic here.
Canon things luna can do :
-turn objects into leaving things
-create lightning and clouds
-make things appear out of nowhere
-shape-shifting (in and out of nightmare moon)
Canonically she was taught to move the stars thus she has some control, my idea is some remained and some where created by her and she has some control over them after Star Swirl taught her. He Canonically goes to the alicorns in G5 asking for help and see potential in Celestia and Luna and teaches them because even though he can understand the fundamentals and theory of magic it is still something our of reach. Like the elements of harmony and how even tho he knew what to do he didn't understand friendship so he couldn't complete the spell unlike twilight.
Hopefully that clears that up.
