Create First React Component

import React from 'react'; 
import ReactDom from 'react-dom';

function Greeting(){
return(
       <div>
          <h4>
            this is john and this is my first componenet; 
          </h4>
        </div>
      );
}

ReactDom.render(<Greeting />, document.getElementById('root'));

Create element by React.createElement.

import React from 'react'; 
import ReactDom from 'react-dom';

const Great = () => {
return React.createElement('h1',{}, 'Hello this element create by create elements');
}

ReactDom.render(<Great />, document.getElementById('root'));