Well, imagine you're the first ever god with a cleric. How are you supposed to know what to reveal to them about the ways of magic?
Generally speaking, even relatively minor/weak/early gods are presented as either pseudo-omniscient (they don't know
absolutely everything, but they innately know anything they aren't
prevented from knowing) or as possessing wisdom beyond the lot of mortals (there's lots of stuff they definitely don't know, but most things, if they
want to know it, they already do or have a means to do so, again unless another power blocks them.)
Of course, since your gods are
created by mortals, rather than
creators of mortals, that whole frame goes out the window, but as Umbran said, that presents its own solution.
Gotta keep my mouth shut on this one.
Omnipotent gods are more monotheism the ancient ones on stories were often tricked or bargained with. I liked Imhotep in 3.0. Level 20 expert divine rank 0 or 1.
[Citation needed]
It depends on the source, time period, region of focus. Zeus, for example, generally could not be
tricked--but some of the deities even older than he is could exert power over him. That's why Eros is simultaneously a child of Aphrodite, love produced by beauty, and also a primordial, ancient force that even the gods fear. The myth of Eros and Psyche addresses this directly; Zeus even cracks some genuinely quite funny (but very difficult to translate) jokes at Cupid's expense because now the snot-nosed brat that yanks his chain has come asking for his help.
Ovid, for example, tends to present a take that simply isn't compatible with your framework. His gods aren't omnipotent, but they're damn close. The problem is, they're
deeply flawed people who abuse their power and position to hurt mortals simply because they possess some special trait or have the
temerity to honestly evaluate their skills. Hence why Ovid's retelling of stuff like the origin of Medusa or Arachne becoming a spider rewrite Athena into being a petty, spiteful shrew, rather than her usual characterization; he was intentionally critiquing Augustus Caesar through the lens of the gods. Legally, Augustus
was effectively omnipotent, but he was also human.
Besides, D&D gods
can be tricked, manipulated, etc. It's rarer because actually using deities as characters is rare, they tend to be more Big Good quest-givers than Abusive Precursor-type deities to screw over because they're enormous jerks. But it absolutely does happen.