I kind of feel that the Dagda is like a father figure to the gods, I am aware that he is also regarded as an allfather and also as a sponsor for Druidry, something I would like to know more about. Cernunnos appears to be in contact with the world of the animals, possibly their spirits, which would place him within a very different role. I see Cernunnos operating as part of a pantheon rather than being the main leader.
Indeed, the The Dagda or “Good God” is also called Ollathair (All Father) and is the “druid” of the Tuatha Dé –Ruadh Rofhessa. The Dagda is also a thunder deity and connected to the thunder tree, the oak. My own musing would be that thunder could seem like a deer’s antlers reaching across the sky, could it not?