I think it is a realistic and energizing saying.
It is realistic, because the celebrities may seems brave and unreachable. But looking from another view, they are just ordinary like us. They have something distinguish and useful. Some of them may have talent in politics, and the others may have achievements in literature. These qualities let them be outsdanding.

It is energizing because, we have our own qualities. The saying gives us a chance to realise the glorious on ourselves. Each of us is an ordinary person，we all have the chance to show our tanlent and skills to the world. We just have to dream big, to show ourselves. Remember, your confidence is the fountain of your energy！

      To answer this question,we must not avoid explaining what is greatness? In my point of view,the answers vary from country to country.We are all growing up watching blockbusters from abroad,I bet you all know the line from Spider man that is 'with greater power comes with greater responsibility'.To Western world,their greatness is self centered,no one would call a janitor great though they work hard everyday to maintain clean streets.While in China here,we pay respects to everyone who devoted themselves to national development and for common good,we call them great.
      We are all just wanderers in this world made of blood and flesh,we are ordinary,we are not much different.What distinguishes us is what we do.If we do things that is good for the country,for society,for people,we are great ordinary people for sure.
      There is other half of this sentence, combined is like Heroes come from peole,greatness comes from ordinary.We all stand a chance of being great!

As for china, it is becoming more and more prosperous. It is the ordinary people who work hard and selflessly are building China. There are so many ordinary men like the submitted above in China, they are ordinary, but they pull together and work hard to built the greet and beautiful furture of China. We figure them are gaint and greet and their spirit are sublime, althougth they live commonly. This is the backgroud of the saying.
In my opinion, everyone born with ordinary. but many people work hard to become greet and gaint. I think these is the surface meaning of the saying. I think the depper meaning of the saying is we should try our best to work and fight against the difficulties to become well. Whatever the problem is or how hard it is, we should never give up and go on forever!
Thank you for watching. What submitted above is just my only opinion, if there any problem, I would like to speek sorry and do hope you can forgive me!

People no matter big or small most of their time do the same stuff, eating, sleeping, working. They have more commonality than their difference. People can achieve any so called great achievment as long as they get rid of their old routine, like a bit generous, not so selfish, holding on a bit longer. it's themselves don't want to make a change. Sometimes it's accumulation each time makes a difference. Just a bit perseverance can make a way to wisdom. Wisdom is not learnt it's made by mindset changing. So it's said greatness is actually ordinariness.

I assume that the ordinary people make our life better. Although they seemed so ordinary, actually they are very grateful.

This theme is inspiring because it empowers individuals to recognize their own potential and the impact they can have, no matter how ordinary their circumstances may seem. It's a testament to the idea that greatness is not exclusive to a select few but is within reach for everyone.

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You confidence  is the fountain of your energy