If I was explaining religion/mythologies to a child; if they are old enough, or once they are, I’d show them some of the following programmes:
Universe: God Star (The Sun)
Wonders Of The Solar System: Empire Of The Sun
A Perfect Planet: The Sun
Wonders Of The Universe: Messengers
I’d explain religions/mythologies and god as the end of a very long line of story telling that started out with early homosapiens looking up at the sky and the world around them and seeing how the Sun changed, affected and provided for all the animals including us. How the Sun was deified and then how other celestial entities joined the Sun in stories with gods or personifications attached to them. Over time, these stories became widespread, over more time these widespread stories, the deities and personifications, stories of natural events and disasters that happened in the world all became what we see as the stories on the books of religions/mythologies.
Some other good programmes are:
Operation Stonehenge: What Lies Beneath
Stonehenge And Archeoastronomy
They show how, from much further back in time than the times of the Torah/Bible/Quran, humans have been making a big deal about the Sun and the other celestial objects in the sky and the seasons. Holidays/festivals that we still have today (that the Christian church changed all their holidays/festivals to line-up with) are all to do with the different points in the sky at different times of the year of the Sun and the stars/constellations.
Understand that religions/mythologies are not real stories, the people in them are not real, the prophets and angels and demons are not real, heaven is. It real, the deity in them is not real. They are fictions, and the root of it all is scientific.