Need help with an essay

The prompt is:"If intelligent life does exist on another planet, should humans attempt to make contact? Why or why not?"
I've bolded the words/parts that I have problems for; these are the parts that I strongly doubt the usage of word. Can anybody please offer some help to correct them? And if there's any other type of problem, please do not hesitate to correct me. Thank you in advance!

As far as we are concerned, intelligent beings must be supportive of pacifism; they're not, as we assume, warlike, unless they have some certain type of severe energy, food or supply shortage on the planet and they possess far more advanced technology that allows a better military equipment. If such peoples(/alien beings) on the planet are struggling hard with the shortage, and the Earth happens to hold a resource of that element or energy, and it's likely that these aliens will start a war in order to invade our planet for what they need to survive.

It isn't without reason that the ancestors of the Americans nowadays exploited the Native Americans on the land by forcing them to leave their original habitat and to move all the way to the western region. And it isn't inexplicable that the Spanish invaders of the Latin America in the eighteenth century employed violent ends to unite the whole region. Those invaders were struggling for survival, just as you and I do on a daily basis, except they were putting thousands of people to deaths while doing it. As these historic tragedies have been submerged in the past, they're trying to make peace with the exploited indigenous by providing them free lands to reside, such as the many Indian Reserves in the U.S., but when the incidents took place, there were no one to provide shelters or defense for the weak. It's not a justice case here, and just like lions must prey on lambs or other animals below them in the food chain, human beings and intellectual beings share the same
relationships of life. The intruders were not definitely inborn evil beings, they were only forced by the contemporary circumstances to take away the lands or mines from the defenseless indigenous, otherwise it would be them that would perish instead. This is definitely something we should learn from the history when it comes to making contact with a certain people or even alien humanoids that we did not formerly know.

Finally, my answer to this question, as you can obviously tell already, is dependent on the circumstance. If they're far more advanced than us, then we'd better take the safe way of staying unconnected from them in order to be on the safe side. And if they're not, I don't think it'd hurt to make contact. And, final note, it's better to trade on a fair term if they have something we demand or need, not to take over the resources by violent ends, after all, we should always treasure lives, there are already too many killings in our daily lives and we should definitely not make any extra ones!