Nice Find! It is a Slavic Icon of the Baptism - the inscription is Slavic (referring to John's recognition of the Lord Jesus as God) - but the Aquarian like fellow is an element typical of Greek orthodox icons, and fits with your own concept, it is a type of water spirit or god of water
I am not sure how old it is, the trouble is icon painting to this day is prescribed in content, materials and technique - the modern ones look just like the old ones! If it isn't old itself, it belongs and is true to an old tradition. Here is another
My method is not to figure out possible Catholic meanings from, for example, the Holy Scripture, but to find Catholic Art that shows similar iconography. What puzzles me is that I often find more examples from early Romanic art (when we are still one Church) or Orthodox Church art. It is truth that on the fall of Constantinople, on 1453, many artist and intellectuals of the Byzantine Empire moved to Europe, mostly to Italy. But it is still odd that later events could have influence on French and Italian tarot.
For example, there were some disputes about the Holy Triad iconography on the East. Finally, at the Great Synod of Moscow in 1667, The Russian Orthodox Church forbade depictions of the Father in human form. This is why the Ikon you have found display the Father as something like a Star. It would be a very nice match for the hidden origin of the Tarot de Marseille Star card. The Father as a Star, connecting to the Holy Spirit dove (the bird on the bushes???) and Jesus, while John, the Christian Aquarius, pours water on a naked Jesus.
The male/female thing does not matter for me on this kind of analysis, because it already have the assumption that the Tarot de Marseille is distorted form of something older. The naked water nymph does not need to mean anything, being only a bad copy of a copy.
But, for me to accept it, I would need to find some Italian (or any west European) piece of art that shows the connection. Or to have some kind of evidence of a Byzantine tarot artist on France/north Italy.