We often wonder if there are aliens out there, but what if we're not the only humans

in the world of space travel an alien is anyone/thing not from your planet
if you travel to another planet you are the alien not any life found there
if humans were found out there they would be alien and not speak any of our languishes
and there would be no reason think any of the same plants or animals would be on their planet
and meeting other humans being safe - WWI, WWII, we do a good job of killing each other so how would that be safe?

That'd be wierd, but I must say I have the same question in my head, and also that 'foreigner'-theory. It makes sense to me, but I just don't see it bieng true.

It is possible that in the long history of Earth humans have progressed technically to the point where they voyaged to other planets... maybe to Mars, etc..

There may well be other life in the universe, but humans are from the Earth and only Earth.