If you show a aeroplane to someone in harrapan age he ll think its a big bird or chariot of GOD .. There is just a gap of 4k yrs . Universe began 14billion yrs back . Earth formed 4.5 billion yrs back ... Now imagine a civilization which is a million yrs old let alone a billion ... Imagine a civilization whr industrial revolution started in 9th century instead of 18th century ....Aliens and ufo conspiracy theories is utter crap...
1. It is extremely hard to travel between stars in short time of an living organism+ the engineering
2. Why would such advance species hide like begams and not arrive in style in front of UN building/ White house etc?
Regarding them hiding like that .. we have no idea how their thinking process social structure might be ... psychology might be totally different ..