That is the test, which is more likely. I ask you to provide an example of a phenomenon studied by science in which the supernatural explanation has provided the better explanation.
Well, yes -- but given that we're talking about the insertion of a very specific human gene, the likelihood of it being there due to "bacterial conjugation [or] viral insertion" is rather tiny.
I ask you to provide an example of a phenomenon studied by science in which the supernatural explanation has provided the better explanation.
Why are we suddenly talking about supernatural explanations? You've shifted the goalposts.