The Shield of Solomon was a Hexagram. It is considered the symbol of the unity of opposites...dark/light, good/evil...and how you cannot have one without the other.
Both the Hexagram and Pentagram are derived from the 360 degrees of the Zodiac. Divided by 5, it gives 72 degrees which is the interval between the points of a pentagram. The number 72 equals 6x12 which is equivalent to 72 cubes or Hexagrams so that each Hexagram will be represent, by it's angles, the 6 Quinancies,(five-degree divisions of a zodiac).
A pentagram's five points represent the Head, hands and feet, allude to the number 5 and the Letter He (in Hebrew). It is considered the Spirit of Life and the Four Elements and the originator of all living form.
Which one to use in a spell depends on what you are working to achieve. You can either creating a banishing symbol or an invoking symbol based on the direction that you draw the symbol.
I don't know too many "passive" women. We all of some of the inherent traits of our opposite. You will recall that the Yin/Yang symbol shows a bit of yin in the yang and a bit of yang in the yin. If you consider that the yin energy comes from the earth, a rising up as in plant growth, it takes a lot of strength to make that happen.
And yes, all things have both yin and yang to them. THe Earth itself is not receiving its powers from an external force, and is acting(not reacting or transmitting) even though it is feminine. The Earth is a creator, and a mother, in the aspect you point out, of giving us nourishment and life, sheltering us, though the Earth is also cthonic, deathly. For flesh rots away, and returns to feed the Earth. Both light, and dark aspects to the Earth, as well as masculine and feminine.
You can evoke female aspects in me, even though I am male. Light can burn and kill and destroy, darkness can act as the womb of genesis, much like female warriors and magi(the Magus, from Tarot, both roles assuming direct action) thrive, just like male priests and oracles(who assume a role of receiving and acting as channels).
Lilith is far from submissive, though she can be receptive. Just look at her lunar associations. The moon shines sunlight, it is a receiver and a transmitter of sunlight, in its own form, which is moonlight.