What if Aliens came or already did come to Earth?

Okay well I was wondering what would happen if aliens came to earth? I’m a person who believes in lots of things and I don’t dismiss things so quickly. I’ve seen some pretty weird things in my life. I know lots of things are real for example ghosts, telekinesis, physics I know they’re real because i’ve seen them all with my own eyes. Now I was wondering why all of a sudden after many many many years of man on earth not getting anywhere suddenly technology explodes in the last 75 years and gets more and more advanced each day since? I know people who say their are already aliens on earth and who helped us and look almost exactly like us which is why nobody can tell. Have you ever really experienced anything paranormal? Your thoughts. Please share.