Maybe some alien civilization does know about us, but it slightly afraid since we spec’ed in the war tree instead of space travel.
They kept letting us advance our war machines until one day they needed us. To help stop a greater evil; since they went space exploration instead of guns
They won’t. While it is unknown if there is intelaigent alien life it is known that none is anywhere close. When distances are measured in tens of lightyears for close thing they can’t get here and back in time to make a difference. Most distances are measured something much larger. Just the milkyway is 25 thousand lightyears to cross.
note that are farthest detectable radio waves have gone maybe 100 lightyears: odds are your are dead before they know we are here.