Look at every other living thing, and how it can adapt naturally and live off of the earth. We are the only thing here that has to alter it's surroundings in order to survive. We have to use animals for clothing, we have to use the trees and earth to create housing and shelter. Our young take FOREVER to become able to care for and feed themselves (some never do...Lol) If we are of this Earth, then we are definitely heavily influenced by something that is not.
No, we are not aliens, because we are native to the Earth. God created humans to live on the earth. Because we were made here, we are not aliens. It is unlikely that humans came from anywhere else, because for as long as we have lived here, we have not figured out how to get anywhere else where there is life.
By definition, humans are not aliens since we came from the Earth. If we came from another planet, then we could be called aliens. It is not likely that we came from another planet. There is scientific evidence that humans evolved over millions of years on this planet to become the creatures we are today.