Why is kundalini energy believed to be feminine energy, taking the shape of a serpent at the base of the spine?

This concept was explored intuitively by psychics who were involved in the ancient Hindu religious teachings and held that perspective. And as this was done by acolytes wanting to be in service to the goddess energies, they naturally saw it through that lens, that the bodily energy that was life-giving was a feminine energy representing the influence of the mother goddess as the source of life, as evidenced through the bearing of young to bring new life into the world, literally. The visualization as a coiled serpent was an intuitive perception of the aspect of the chakras being a kind of energy vortex, a ring of energy that is in motion and has a circular configuration as this is the means of organization, to widen or narrow, and governing the flow of incoming energy and to tune it, in a sense, to change the frequency by the degree of constriction. So this was seen in the mind’s eye of psychics as a circular coiling of energy. And associating it, as well, as a life force, imposed the symbol of a living thing with similar physical characteristics in the form of a coiled serpent, as this could also extend and was visualized as the energy rising up through the body from the root chakra, much like a coiled serpent rearing upward cobra-like. So this is a good illustration of the limitations of attempting to understand the universe solely through psychic perception without a secondary and higher form of direct communication, as via accurate channeling. There are many things that are perceived in reaching an accurate target for exploration, but the difficulty enters in with the filter that inevitably is brought to bear by individual psychics attempting to understand what they are perceiving intuitively, without prior knowledge and awareness of specific details in an accurate sense. There may be many varied interpretations of the exact same phenomenon by a group of individual psychics, all tuning into the same thing to probe it and come to a better understanding of its purpose and function.