How do historians know that cave paintings has special meaning to those who created them?

Historians believed that Cave painting has special meaning to those who created them because they found out that the paintings vary significantly according to the experience and cultural maturity of the artist, based on the nature and contours of the rock surface, the strength and the type of light and the raw materials used. As the artists expressed their choice whether or not the outline of the cave wall made it significant since in engraving or even sculpting would be applied to boost volume and relief. Historians thought that cave paintings was created for ceremonial reasons and perhaps in connection with social, supernatural and religious rituals.