With FTL being possible, there are few reasons to believe, concretely, that no other civilizations can not reach Earth. The possibility is always there. Common events performed by humans today would have been considered “magic” just a century or two ago.
FTL, though, is not possible due to E=MC*2.
The inertial energy you generate by moving at any where near light speed converts to increase in mass to the point you can’t be pushed any faster.