Evolution and original sin

Do you believe that people ( I won't use "beings" or "aliens") from other planets or dimensions have been instrumental in guiding the human race's evolution?
If this is a truth, a recurring question is: "Where are they? - Why don't they come by and continue to teach us the technologies they have fashioned?" Basically, the human race has not evolved in the way they thought it might. Their intercourse with humans tens of thousands of years ago did not produce physical bodies which were any better than theirs. Our "wiring" still contains the propensity for violence which they themselves experienced. Their DNA is flawed, and so is ours.
Over the years, they have inspired and interceded to teach humanity how to overcome this propensity toward violence -- teachers, masters, gurus in every age have reiterated the dictum: "Love one another - forgive one another - love your enemy - do no harm to another living being - walk the extra mile - do to one another as you would have others do to you, etc., infinitum" - words of encouragement offered by thousands more souls than the ones we have put on a pedestal - Buddha, Jesus, Francis of Assisi, Confucius, Lao Tsu, Lincoln, Gandhi, Cayce, MLK, etc. And still, our violent animal nature tends to override the efforts we make to change and allow our divine nature to shine through.
I often struggled with the idea of "original sin", the sin we are told we are born with (in the Catholic tradition). How can a newborn carry any sin at all? But yes, we are born with a "sin" - the propensity toward violence and behavior which breaks our connection with one another. And every spiritual master, teacher, guru has taught us how to overcome it - by learning to Love - by practicing Compassion. It is Compassionate Loving which reconnects us with one another, which establishes peace in one's own heart, and which can transform another heart to love and be compassionate. The more we learn how to connect, the more we can truly bring what Jesus calls "The Kingdom of God" into this material experience. (The Kingdom of God is already here among us - we have lost the ability to "see" and experience it.)
The best mantra to learn and to repeat in our minds, is: "Everything is connected." Because in truth, everthing IS connected, on the level of Being, in the heart of hearts of Limitless Being, from which everything, ALL of Life, springs. If we can only learn that we are really all the same, with variations, we would not decide to harm one another. For then we would understand that in harming others, we only harm ourselves. And when we harm ourselves, we limit the expression of Being, who only wishes to create new and wonderful ways to be.
I certainly recognize all the good which is done in the world. Without it, we would be cannibalistic animals. But it seems that not everyone in the world sees the good which can be done through even a minimal practice of compassion. Perhaps if they did, their hearts could change, too.
So, why don't our ancestral "teachers" come back to help us? Why don't they show themselves and teach us more? Because we have not learned to love. Our ethics - as a species - is terribly flawed, and there would be those who through egoistic and misguided faith would misuse the gift of knowledge these people could share with us. Namaste.