As for invisible aliens living among us, why should they have come? To bask in our reflected glory? If they managed to get here they are so much technically advanced we're just ants to them, so why hide? To spare the deluded feelings of superiority of some primitive life form? I'll be kind and just say "unlikely".
Perhaps aliens are developing their codes of fieldwork ethics? The early alien visitors were quite hands on and tended to interfere culturally (lots of fire, brimstone, tablets of stone, favoured tribes etc.). For the last 1500/2000 years or so they have basically withdrawn from active intervention (though occasionally field workers can't resist picking up the baby turtle and putting it into the sea before it gets eaten by the seagull/commit mild miraculous acts). Nowadays they just watch, probably gently banging their tentacles against the wall of their invisible space crafts each time they read a Trump tweet.