Aliens as Gods
Some past UFO events are believed to be influences on religion ... or even the beginnings of such. More likely, an alien visitation way back when is a mistake and a good justification for not interfering in the development of "humans".
Imagine what might take place in the minds of primitives upon having a close encounter with the occupants of a landed saucer.
Grog meets his maker
Grog is walking down the path to his sheep when he beholds in the clearing a landed saucer with strange beings standing around. He thinks first, "Feet don't fail me now!" ... but they don't work. He's just too scared ... he's petrified.
Seeing this, one alien says to the other, "Let's bring him over and give him milk and cookies. That will put him at ease.". So, they 'float' him on over and set him down on a rock and hand him a cup of milk and two Keebler Coconut Chocolate Chip cookies (made with the recipe back in the 70s). Grog doesn't know what to do now, He guesses that the milk is to drink but has never seen a cookie. He is informed 'telepathically' that he is to drink the milk and eat the cookie. So he proceeds to jam one cookie in his mouth to please the gods.
But another alien (me) gets upset when he sees Grog eating the cookie in the incorrect way. Obviously, you are supposed to break the cookie in half, then, take the half and dip it into the milk ... and ... giving it the proper soaking ... lift it out and eat it then ... with just the right amount of saturation ... in 'quarters', i.e. soaking one quarter leaving the upper quarter dry and held between the thumb and forefinger of the right hand, then dipping the remaing quarter of that half by fully submerging it undermilk along with the thumb and forefinger which them must be licked dry ... (there, I've said it and I'm glad). That is, there is a ritual attached to eating the alien's food ... the food of the gods. Grog is now sent packing with extra cookies (but not the milk) to take on his journey and share with the other shepherds and sheperdesses. Grog likes the cookies ... they are, after all, Keebler Coconut Chocolate Chip cookies (which are the best cookies in the known universe - even better than milk-soaked Oreos - but only if they were made with the 70's recipe).
The aliens think they have done well by the primitives and congratulate themselves thoroughly even though they have 'lost their cookies'.
Time marches on ...
Another alien group returns two hundred years later and finds a more elaborate civilization. Its ruling clique is made up of priests wearing white robes and headdresses that make their heads seem all out of proportion with their bodies. They conduct 'services' every three months or so (when the seasons break).
The ritual associated with the services consists of breaking a humungous, round, flat piece of hardtack into two roughly equal pieces which are then dipped into a great bowl of pinkish liquid. Then, the pieces are further broken off and given to "the faithful" who come up and kneel and stick their tongues out with their eyes closed and eat the soaked hardtack.
The pinkish liquid is found to consist of three parts goat's milk and one part human blood which is draining from a corpse lying on a slanted slab of rock. The general area is festooned with skulls on poles of course.
These aliens are mystified by the gross, unbelievable behavior of the natives and, conferring amongst one another, decide that they are glad that "We don't live here!".
You can't give anybody anything for free. When you give them something, you are also taking something from them. You are taking a bit of their autonomy ... their right to rule their own behavior. This is especially true when the gift is something large and the recipient possesses, shall we say, a nascent intellect. The contact with the aliens has given the natives a philosophical direction which they would not have taken in response to their own lights. That direction is inconsistent with their present status in their present environment.
Now, they're all fucked up.
Well, you could just give 'em everything you've got ... educate them, show them a better way ... hmmmm, why not just kill 'em all and put your own progeny on the planet, i.e. colonize it. But what good is it to have JAPLM (Just Another Planet Like MIne)
The point here is to let it be and see what interesting things develop on their own.