Having read quite a few books and articles on the subject this is my take on it.
World governments have some deal with select types of aliens, they allow them to take embryos and hybridise, they have to do this as they tampered with their own genes and are attempting to put the genie back in the bottle, in return the government's get mass chipping and some new technology knowledge, the really benevelant aliens are kept away from Earth but occasionally get through and try to deliver messages, some may be able to time travel.
I may go and look through cases to find those where I think the benevolent type have manage to get through, I was going to link to one in Wikipedia re a TV interupion from years back but I see it has been altered to make it look more like an easier hoax to commit.Last time I read it , it seemed as if it was impossible to do in the day.
Here it is if you wish to listen,need to scroll down a little
https://www.historicmysteries.com/un.../vrillon/3112/