Hello Gregg,
The ancients did know all about that which we are just beginning to re-discover. Nothing can be more helpful to understand the underlying reality of the material universe than symbols and they, the ancients, knew it.
In this regard, all the stupid philosophy of our time cannot possibly compare with symbolism, where as far as understanding God, the universe and our selves is concerned, the simple circle-and-dot symbol is worth a million pages of abstruse writing. In fact, the more you study it, the more you grab the significance of the Principle and how everything else depends on it to exist.
There are other symbols derived from the circle or the square than can make you reach higher states of being or get into deeper degrees of reality. Sometimes merely watching a symbol can make you perceive other dimensions and enter blissful states of being within yourself.
What you say about the kids drawing circles and rays is most interesting, as is what you say about the Hunab-ku. No wonder those kids can get into those states, their minds have not yet become tainted by material nature.
About blood having a cosmic significance: whole treatises could be written about it, but it may be enough to say that as you breath in prana-loaded air, God's spirit, coming in on the rays of the cosmic wheel, is circulated by blood throughout the body and the brain, thereby activating the crown chakra and inducing a higher perception of reality both inside and outside.
In this regard, a beautiful tradition from esoteric Christian circles has it that Jesus' flaming heart radiates life and love, and his own Spirit, from the center of the universe out to the entire cosmos and into the last atom; and that this is reproduced inside our bodies with our own hearts radiating life, love and God's spirit also to the last atom in them (provided that we are not yet too contaminated by the material world, in whose case I don't think those life, love and God's spirit can be too saintly).
However, in order to more than merely exist, in order to experience those really higher states and know those deeper degrees of reality, we need to consciously let Him in the first place by means of some preparatory action, like meditation, mudras, symbols, sacred music or even a little conscious breathing. It is like radio sub-stations, they will not broadcast the main station signal unless they are properly tuned in with that main station.
Of course, little children do not need to make any preparatory work, they already have the 'Kingdom of Heaven' in them. There are quotes in the Gospels and many other sacred texts, for example the Tao-te-ching of Lao-tzu, where all this is hinted at.
Blessings,
Miguel