Regardless of whether you are a miner or a missionary, you can’t just turn up unannounced and expect a friendly reception. One false move and there is the likelihood of being attacked or killed.
Presuming you are without the backing of troops, that means arriving somewhere, not knowing the local language, and needing to show demonstrate that you were either highly superior, no threat, and/or had some mad skills.
- It is hard to convince someone of anything unless you share a common language
- It is hard to show off mathematical skills, to someone who knows nothing of math or numbers
- Conceivably you turn up just before an eclipse, but that takes great planning and luck
- Medicinal skills, perhaps, but they were likely very hit and miss, and you need someone to be sick at that time
There is repeated symbolism in the Neolithic Near East of cattle and double-head axes, and it could be as simple as that. Demonstrate superiority with bronze tools and weapons. And strike awe with dried magic mushrooms. One or the other is surely plenty to at least the locals thinking that this could be good for them.
Language is a major barrier, so it is implied that the elders were clever enough to learn new languages quickly, and stay around long enough to do so. Missionaries throughout history have managed to achieve this, so I do not see it as being an issue. But we do know that they needed years before they could achieve anything of worth.