Shadow education secretary Angela Rayner said under Labour "every child matters" while the Tory government's record on schools "wouldn't survive their own Ofsted inspection".
Ms Rayner, from a single-parent family - who left school, pregnant, at 16, and with poor grades, told the National Association of Head Teachers (NAHT) annual conference, a child's life chances should not be decided by where they are born or who their parents are.
She said: "I went to a so-called failing school and it was that school, those teachers, that head teacher, those support staff, all of the people there that made me the resilient person that can stand in front of you today, that has become the education secretary elect and has done so well.
"Because you taught me about making sure that you respect yourself and you are valued and loved regardless of what other people say.
"That's what good schools do.
"And my school was considered a failing school, you didn't fail me, you created the person I am today."
The MP said the Government's record on education has meant targets for teacher recruitment had not been met for five years, with more teachers now leaving rather than joining the profession and half a million children in "super size" classes, while teachers have had their pay capped.
To applause from delegates at the conference in Liverpool, she added: "They wouldn't survive their own Ofsted inspection."
Labour, Ms Rayner said, was committed to creating a "cradle to grave" National Education Service, "a meaningful and radical transformation of our education system", asking the NAHT for their help to shape the policy.
But one head teacher, Simon Kidwell, from Sandbach, Cheshire, said funding cuts had left schools "on our knees" and asked if Labour's commitment to provide free school meals for all primary school children, costing £950m a year, was "best use" of public money.
Ms Rayner said: "I remember being the free school meals kid and it's not nice being stigmatised and that's what's happening to our young people."
She suggested a Labour government would give extra funding to education on top of free school meals for all.
Ms Rayner said funding spent on education was money well spent and an investment for the future, instead of spending money on people later in life, in the wrong place at the wrong time.
"People say, well that's ridiculous, how can you afford it, Labour's 'spend, spend, spend'. But you know what, we are spending so much money on making children and young people feel bad and then catch up at a later date in adolescence where we are having to spend money in the wrong place," she said.
"We do it with adults and social care as well. When I was a home help we spend money on putting people on hospital trolleys instead of providing them with community care.
"So if we invest in our education system and get it right and get that resource in where we need it, it will save us money."
She added: "I know it has been very difficult for you over the last eight years, I know you feel let down by politicians and that they haven't been listening.
"I want to assure you that we are listening. I am listening and together we will build a national education service that puts all of the children and all people at the heart of it."
Paul Whiteman, general secretary of NAHT, said: "We'll be engaging with Labour's consultation on their National Education Service and their other policies which affect young people.
"As I said in my conference speech, education is the best route to a happy and fulfilling future for our young people, and the only silver bullet to solving the problems in our society."