I think those are good questions to ponder, Ygrec.

mala-- I think your belief is cool! do you mean that you believe they have been here?
My mother in-law believes that aliens were here and are very adept at staying "under the radar".

I, myself, am still on the fence.... can't decide....
I do think there is other life out there in the cosmos-- but... whether they've visited here? hmmmm... I'm just not sure..... (wish I was either for sure they have or for sure they haven't-- this on the fence stance is disconcerting for me)