NO FLAME WARS. Its like if you compare us to weird living things, we are considered aliens to them and they are considered aliens to us. But if you compare a typical human to us, we wouldn't think that he/she is an alien.
When aliens invade, people will panic and the landowner won't bother to collect rent from you. When aliens invade human will be sure to interfere to protect earth and not give a warm welcome the the aliens, like " Hi, welcome to earth. " When human interfere a war will break out, But not in all case
Erich von Daenicken postulated pretty much the same decades ago. I didn't buy it then, I don't buy it now.
The idea of course is that we could never have evolved here because the earth isn't old enough, which is utter BS.
This question is completely determined on the way the individual would define alien. Otherwise it's quite honestly just silly to even ponder. If the definition of aleins is did we come the same raw materials that are floating around just about everywhere else in the universe that may have more than possibly sparked life elsewhere as well. Or even that the materials that have made us may have been part of life in the past. The answer is 100% yes. It's probably one of the few questions science will ever have to doubt in the least.
"Even if they find DNA similarities between Earth and Mars it doesn't mean a damn thing because the same DNA similarities could exist between all planets everywhere in the universe."
Sure it is possible but not likely.
You might wanna rethink that one. You kinda contradicted yourself a bit. You say it is possible but not likely. Now calculate the amount of times the similar type of circumstances may occur. It's possible and likely.