I think we would agree that the Celtic peoples, in their mythologies and lore, had a notion of the cycles of life – circles of existence. This is the reason, I believe, that no authentic ancient Celtic creation myth has come down to us directly, despite numerous attempts at speculating what it might have been. I’ve read all kinds of hypotheses and, as beautiful and poetic as they are, they just somehow don’t ring true. Jean Markale proposed some interesting ideas as well, but they remain highly conjectural at best. Now, what about my idea? Perhaps the Celts didn’t have a creation myth because they saw things in a different way – no beginning and no end – just like a circle has no beginning and no end and every point on a circle is connected in both directions to any other point or just like how energy cannot be created and cannot be destroyed but only transformed, i.e. the First Law of Thermodynamics.
I stress, this is just my own idea, but just because other religions/belief systems had some kind of creation myth does not necessarily mean that all religions/belief systems had one or viewed things in remotely the same way, does it?