Complex sentence: Completely unsourced, started on the creator's own user talk page and then incorrectly moved into projectspace instead of mainspace, but because there's no sourcing and no credible claim of here, there are no grounds for moving it into articlespace at all.
Split into simpler sentences: Completely unsourced, started on the creator's own user talk page and then incorrectly moved into projectspace instead of mainspace. Because there's no sourcing and no credible claim of here, there are no grounds for moving it into articlespace at all.