That was us being hostile not them. I think it is likely that some species are indifferent to individuals but might care for us as a species or DNA repository. And hostile in a way that they modified our DNA to be able to utilize us more efficiently. As is described in the Greek Mythology were Zeus complains about the humans not following their orders and their resistance to them being put to work by the Gods. His solution, create conflict among the humans themselves, especially in the most common and strong relations humans have, between man and women. And besides that Zeus said he was going to split the human beings in half so that from the moment (s)he is born (s)he isn't even aware of the other half of him/herself. Divide and rule.