The first Old European cave symbol I identify in the video book list (top left, see video below) of Old Paleolithic European Cave Symbols is of the same form as the rune Hagall (of the Younger Futhark), known as the "Mother Rune" and "Mother Of All Runes" by many runologists. In runic folklore, Hagall is symbolic of transformation, evolution and Divinely Creative Consciousness. It is also associated with Goddess. Some runologists may refer to this mysterious hidden Goddess Consciousness by the name Runa.
The Old European cave symbol that I identify as the rune Ing (Ingwaz) in the video (my Father Rune) carries many meanings, one of which is of an "empty space." In Kabbalah, it is taught that God contracts part of His Infinite Light (Aur Ein Sof), making a finite "empty space" in which the process of creation unfolds and all creation exists. This process is called Tzimtzum.