Of course it is possible, but this simply illustrates my point that there is no more evidence for the existence of a Christ Myth than there is for a historical Jesus. Therefore the cosmic myth notion is as improbable as anything it seeks to explain.It is possible that there was a preexisting celestial being Jesus that was conflated with an obscure teacher of that name who came later which means you could have the Christ Myth and [obscure] historical Jesus coexisting.
In fact it is more so, because our sparse early sources (assuming they were not all forged by packs of insane liars in the fourth century or later, as dejudge asserts) imply the existence of a messianic cult preaching in the name of a person, although they tell us almost nothing about the person. They don't relate the pre-existence of a cosmic cult with supernatural beings dwelling, and being incarnated and sacrificed, in the metaphysical Sublunary domain.