Is using a header the only way to input text into a form?

Hi, 

No. You can add a Text item using Basic Fields menu. Then double click on the added box and add any text to your form.

If you need any further intformation please ask. Hope this helps.

No, you can also use Text field to add your text to the form. With Text field you can also style your text. For example you can change font size, font family, font color, etc.

Hope this will help. let us know if you need further assistance.