So basically the deities could actually be extraterrestrials with technology a few centuries ahead of us. They settle down on Earth and start consolidating local power. After showing off their powers they are immediately deified. The deities then provide them with their own mythos to keep the population subservient.
Depending on the level of advancement of your populous, a simple metaphor for creation might be more suitable than factual explanations of complex physics. It is hard enough to teach algebra to students who've already had years of arithmetic, let alone hunter gatherers.
Regional metaphors will be more applicable and will spread faster, facilitating your rise to power. Maybe the humans had creation myths already, and the new deities just latched onto it for simplicity?
The deities can help build up and task their civilization to harvest crops, build monuments, and conquer neighboring domains.
They would avoid direct war against each-other because at that tech level weapons would be capable of sterilizing entire planets.
Perhaps they are enjoying playing around with the civilizations of Earth, much like a game of Risk? Flipping the game board and attacking your opponent directly is frowned upon.
These deities could be genetically engineered to have pretty much whatever physical form they want. They wouldn't even need to conceal their technology, it would still be viewed as magical.