** I think that if Zeus is real, then he knows where he came from; considering that posibility, don’t you think that he has a responsibility to tell you?**
He comes from Cronos and Rhea, according to the tales. Are you sure you’ve read them?
And why do you think that the ultimate source of reality does not contact us?
Because I have no experience of any such.
** Why would you give worship to a lesser God like Zeus, if you can give worship to Ultimate reality?**
I do not know what an ultimate ground of being might be, or even it if it is. I did not say that it was a God. I give worship and piety to Zeus because He is worthy of such.
What interest does Zeus himself have in humanity?
You will have to ask Him. I do not fully know the minds or motivations of the Gods.
Come up with any examples of Zeus demanding human sacrifice for spiritual favors yet? Have you read the story of Zeus and Lycaon as recorded by Apollodorus?
theoi.com/Text/Apollodorus3.html
"[3.8.1] Let us now return to Pelasgus, who, Acusilaus says, was a son of Zeus and Niobe, as we have supposed,142 but Hesiod declares him to have been a son of the soil. He had a son Lycaon143 by Meliboea, daughter of Ocean or, as others say, by a nymph Cyllene; and Lycaon, reigning over the Arcadians, begat by many wives fifty sons, to wit: Melaeneus, Thesprotus, Helix, Nyctimus, Peucetius, Caucon, Mecisteus, Hopleus, Macareus, Macednus, Horus, Polichus, Acontes, Evaemon, Ancyor, Archebates, Carteron, Aegaeon, Pallas, Eumon, Canethus, Prothous, Linus, Coretho, Maenalus, Teleboas, Physius, Phassus, Phthius, Lycius, Halipherus, Genetor, Bucolion, Socleus, Phineus, Eumetes, Harpaleus, Portheus, Plato, Haemo, Cynaethus, Leo, Harpalycus, Heraeeus, Titanas, Mantineus, Clitor, Stymphalus, Orchomenus, . . . These exceeded all men in pride and impiety; and Zeus, desirous of putting their impiety to the proof, came to them in the likeness of a day-laborer. They offered him hospitality and having slaughtered a male child of the natives, they mixed his bowels with the sacrifices, and set them before him, at the instigation of the elder brother Maenalus.144 But Zeus in disgust upset the table at the place which is still called Trapezus, and blasted Lycaon and his sons by thunderbolts, all but Nyctimus, the youngest; for Earth was quick enough to lay hold of the right hand of Zeus and so appease his wrath.
[3.8.2] But when Nyctimus succeeded to the kingdom, there occurred the flood in the age of Deucalion; some said that it was occasioned by the impiety of Lycaon’s sons."
Note that the flood mentioned in the age of Deucalion was told as the almost complete destruction of humanity because Zeus found them to be too wicked and impious (sound familiar?).
theoi.com/Text/Apollodorus1.html
“[1.7.2] And Prometheus had a son Deucalion.105 He reigning in the regions about Phthia, married Pyrrha, the daughter of Epimetheus and Pandora, the first woman fashioned by the gods.106 And when Zeus would destroy the men of the Bronze Age, Deucalion by the advice of Prometheus constructed a chest,107 and having stored it with provisions he embarked in it with Pyrrha. But Zeus by pouring heavy rain from heaven flooded the greater part of Greece, so that all men were destroyed, except a few who fled to the high mountains in the neighborhood. It was then that the mountains in Thessaly parted, and that all the world outside the Isthmus and Peloponnese was overwhelmed. But Deucalion, floating in the chest over the sea for nine days and as many nights, drifted to Parnassus, and there, when the rain ceased, he landed and sacrificed to Zeus, the god of Escape.”
Doesn’t exactly sound like a God who the Greeks believed regularly demanded human sacrifices, does it?