Some misconceptions I must dispel. According to the Fifth Law of Mechanics, this is quite impossible. I am not a subversive spy or the advance man for an invasion front. Conquest of such a distant place as Earth is pointless, and subjugation of your race into slavery is morally repulsive. I am also not scouting out your natural resources to see what can be stolen.
Space travel is too difficult to lend itself to the exchange of goods.
The fact that I can get here at all should demonstrate to you that our technology is so much more advanced than yours that your technological treasures are like children's toys and do not interest us. The only practical purpose for interstellar commerce is the exchange of information. Oh, the other possibility you mentioned is not true either. I am not a religious missionary. The plain truth is that I am sent here by the Department of Comparative Cultures of the World Council of Countries and Independent Jurisdictions to study your society, your folkways, customs, morals and culture.