Imagine a farm in Kansas, a boy wakes at 4AM in the morning to help his dad with the harvest. His mom brews coffee, pours a glass of cold milk, fries eggs and bacon and toasts bread.
The morning/night is cold, but the home is warm. Mother, father and son sit at the old kitchen table to enjoy their breakfast and each other's companny. These are good people, these are happy, simple people... Except the son is not from Earth. This has never been an issue. His parents love him profoundly and with equal intensity he loves them back. The boy has no idea he is from another planet, there has never been a reason to tell him. Why would anyone put such a burden on a kid anyway? But now the time has come. Lately the boy has developed amazing abilities. These abilities are confusing him, causing him pain and joy. He is strong - beyond meassure, he can see through walls, hear a cricket miles away, run faster than any car, make Smore's with his eyes and much more - but he doesn't undertand his abilities and many times he can't control them. There had already been three minor fires in the farm and several needs for wall repairs.
The parents are worried how can they help their son understand or control his abilitiles? How can they protect him from the prying eyes of the world? How can they provide the moral compass that will guide him on the use of his abilities? How can they make sure that deep inside, he'll always remain the incredible goodhearted boy who woke up at 4AM today to help his old man in the farm? The selfless boy that spent his Saturday helping his friends with math homework instead of playing ball? The caring boy who a week ago offered to carry Mrs. Lang groceries, so she could rest her broken leg? How can they provide the guidance - for when the time comes, and it will come - that will make their boy able to differentiate between good and evil; selflessness and selfishness; action and indefference; love and anger; hope and fear. The guidance that will let him use his abilities not out of fear, but out of hope? There is so much good in this boy and it's their burden to nurture it, to guide it, to let it grow - so one day; when their boy is man - he will know how to act...
Here is where the path divides.
If you have read Superman comics over the years, watch the animated series or the old movies - you know that his moral compass rests squarely on his upbringing from the Kents. His abilities may come from Krypton, but his humanity - who he is comes from Kansas, from working in a farm and growing up in a loving family. As a man he knows how to act because his parents have taught him to be selfless, to be basically good and to love his fellow humans - in his own eyes this boy, this man thinks of himself as one of us. Yes, he has these awesome abilities, but they do not define who he is. Only what he can do. As any of us, he is defined by what he choses to do with his abilities, and what he choses is simple. He choses to help. No conflict, he understand what his abilities allow him to do and he choses to help.
In MoS and BvS, this boy also loves and is loved by his parents, but his parents are not hopeful. They are afraid, and the boy can sense their fear. They are not, like the classical Kents, a beacon of hope, of kindness. They are more like us, they are scared, they are selfish. They want to protect their son, and the rest is secondary. And who could blame them? How many parents would lay everything and everyone for their kids?
The DCEU Superman, grows in a farm, where the Kents provide love, but not moral guidance he needs. He grows in a farm, where he is taught to hide, to fear the world, to do nothing, or at most do good only if he is sure no one can see him - no matter the consequences of inaction. The boy, to his merit revels against it, but he is conflicted. "Should I have left them die?" he asks. "Maybe" his dad's answer. As an adult, when looking for guidance "Be their hero, be their angel, be their hope" his mom tells him, just to finish it up with "...or be none of it, you don't owe this world a thing". Or his words to his girlfriend " No one stays good in this world"... All this conversations, carry the same message: defeat, lack of hope.
The Kents in MoS and BvS have raised a man who is at conflict with himself. A man who is so afraid of revealing what he can do, that he willingly let his father take a risk he should have taken and then die (albeit at his own father request) to keep his secret. A man that to protect his mother endangers a full town, a man afraid, like anyone else, to loose those he loves.
Not as a conseuence, but in spite of his upbringing, this man is still willing to risk and give his life to save his adopted planet. He is still willing to believe in second chances and once his powers are out he is trying to help. For this Superman, selflessnes comes out in spite of his adoptive parents and not from them. That is why, while classical Superman represents pure, unadulterated hope and love for humanity -the man of steel represents the conflict between fear and hope, with neither of them getting the upper hand for too long.
To some, this might be a more nuanced, even more interesting Superman. To me, although I enjoyed both MoS and BvS, this wasn't necesary - Superman is supposed to light the way not because he is powerful, but just because his parents taught him to be kind, to be loving and to hope for the best in all of us. Superman is an aspirational and inspirational character... His conflict should be his inhability to help everyone, not wether he should help at all.