I'm pretty sure that there is a huge amount of other species out there in the great unknownbut I'm slightly skeptical on whether or not we've been visited by them.

Firstly it would require a species intelligent enough to aquire space travel to stumble across our planet in this short time we've been here.

Secondly this would require faster than light travel which in our current understanding is impossible, we could just be unable to comprehend how to achieve it though.

Also what reasons would they have for travelling here, if they want to communicate why don't they, if they just want to observe or collect samples why are they clever enough to travell all this way and yet still get spotted by what would be to them a massivly inferior species.