Go ahead and poke a little fun at the analogy if you will, but it is a good one, in this sense:
The arrival of Europeans on vessels that could carry 100 men, with weapons of steel and vests of armor, would have been as unknown to the Indians, as the arrival of Aliens would be for us.
And what would you think the arrival of a new culture to this planet would think of us. Specifically:
** We allow well educated men and women to cut unborn babies from their mothers womb and then kill them, just as they are able to sustain life.
** We have an entire culture of people who encourage their children to kill themselves, as long as they take others with them.
** We have had experiences, in recent times, where entire nations have grouped together with part of the result being the mass slaughter of millions of other people.
** We have had numerous governments organize themselves in such a way as to actively encourage the starvation of millions of their own people.
** We have millions of people here in the United States willing to vote for Hillary Clinton for President.
OK, that last one may have gone too far. But, seriously, you are trying to weigh the good against the bad. Not all Native cultures were the savages you are portraying them to be. And the death of 70% of their population through disease is a difficult one to overcome with the good things that have then happened.
Good heavens! Hillary as President? Surely that would doom us to a new stone age and lives, like those of the Indians, that are nasty, brutish and short!
I remain unconvinced. Had not Euros arrived, the Americas would be mostly in the stone age today. Again, I already gave credit to the few bits of civilization in Meso America. And I also noted that as of the arrival of the Euros, they were essentially failed states.