Ancestral worship is the veneration, feeding and/or adoration of ancestors who have come before you and resulted in the creation of you -- it is a form of spirituality. Some of us believe certain aspects of the energetic biobot systems we call 'human' are eternal. Some call it the spirit, soul or essence of the individual. It is the physically invisible, yet ethereally visible aspect of a person. Ancestral worship hinges on the belief that humans, outside of a physical body, come into a more powerful, more grand, more deified version of themselves, handy for assisting other family members who remain in the 3D or carnal world. They can feed of the essence of food and drink left for them and spend money in their plane, that is burned for them in this one.
Once an ancestor passes to the ancestral plane, they remain alive and accessible for a time. Even if they reincarnate, their Higher Self form can still interact with your spirit in the dream state. When you reincarnate, your entire energetic body is not in the body, but there is an attachment that remains to the universal plane. The part of the universe that gives you life is sometimes called your Ori.
Who Are My Ancestors?
Your ancestors are your creator. They are the universal-manifested physical presence in your particular bloodline. You are the reincarnated them. A fire that lights a match does not cease to be a fire, even if it lights 12 other candles. Each flame is a flame in and of itself, made from the original flame. Such is the ancestors.
So who made you? You have water ancestors, mineral ancestors, metal ancestors, animal ancestors, human ancestors, energy/light ancestors, etc.. Typically the older an ancestor is, the more likely they are to have become righteous or deified, which many religions call God. Whoever or whatever made you is your ancestor and you are more oxygen than anything else so your ancestors come in various forms, mostly invisible to the naked eye. What stones do you gravitate to? Do you feel at home swimming in the ocean? Is there a past ancestor who you resemble to a tee? Do you have an affinity to a certain bird? Have you ever been told that you resemble a certain animal? Have you ever been in trouble and been visited in the dream world by a speaking person or animal who seemed familiar, but that you did not know, who offered you assistance or advice? It is likely you have encountered an ancestor, whether in the dream world or in waking reality.