There's three ways to godhood, I think:
1) Fulfill prophecy (the "Missionaria Protectiva" rule).
2) The massaging of a real person's deeds until they become superhuman. In this case the person can specifically have denied they were superhuman, much less a god but it might happen anyway.
3) By doing "impossible" things that are not well-explained (ignorance).
Since #1 and #2 don't really involve technology, I'll just discuss #3.
I'd like to give a "TL gap" rule ("if you're X TLs above your observer you're a god") but given how "tight" the Traveller TL chart gets past about TL5 or so, I don't think it's possible.
Impossible When beings do something that is considered "impossible" they are on their way to godhood. By "impossible" I mean violation of the "known" natural laws of the time in a fashion that many people in the observing culture would agree is "impossible." A culture where everyone believes with the correct knowledge and resources anything is possible will probably be pretty hard to convince you're a god.
Instantly It helps a lot if your impossible deed is done in a short period of time, preferably "instantly." Being able to de-age someone is impressive enough. Touching an old man, a flash of light, then he's a young man is vastly more impressive than using magic that will de-age him over the course of months.
Ignorance: Also, you can't explain what you're doing, at least in a fashion the people would understand. Of course, the biggest no-no is explaining that with the proper knowledge and tools
anyone can do this. You don't even have to speak to your potential worshipers; you can just ignore them and continue to turn mountains into plains (in search of Lanthanum but they don't need to know that). In fact, this helps often helps. Most humans are secretly egotists and masochists, so we love to be spurned or ignored by our superiors who have better things to do than to explain what they're doing, since this is our tendency given the opportunity and envy is a great way to generate worship.
Typical impossible things: Flight through air, manipulation of matter without visible contact, visible "mastery" of natural forces considered uncontrollable (like lightning or driving off the evil spirit eating the sun), knowledge of distant events in "real time", reading people's thoughts, bringing people back from the dead, de-aging, healing of afflictions considered incurable, or perpetual youth.
For instance, in many lower tech cultures, the idea of a person flying through the air is impossible. Therefore, regardless of if that person has a "flying chariot" or not, a being that can fly through the air is on his or her way to godhood. You can explain that your airplane is not really a mechanism of your godhood, you could even show them the physics textbook explaining how it works (provided they don't understand the math), but without fully explaining it they're still in "ignorance." Even in a higher TL culture with airplanes, you could probably impress a lot of people if you could just jump into the air and fly off without any visible equipment.
Please note, some people reading this will say, "you could just be a 'demon' or a 'spirit'" but the dividing line between a 'powerful spirit' and a 'god' gets pretty hazy; both are worshiped and/or appeased. Different cultures will have different names for "gods" - that a being is treated with awestruck reverence/favor currying (worship) and fear of offending the being is my definition of godhood.
1. Is it immortal? If it has a measurable lifespan, it's not a god.
2. Can it be killed? If a way can be found to kill it, then it is a living being, not a god.
I agree with most of your points except these two. While forum rules forbid me from mentioning specific religions, we had (and have) religions on this Earth where their higher beings are specifically able to be killed or die through other means.
In some cases they may be reborn, but in others once they die, that's it. This does not prevent them from being considered higher beings, however and indeed their deaths may be necessary as part of some "end times" battle or the regeneration of the cosmos.
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