Yes these static pages have a What-You-See-Is-What-You-Get Editor. So you can add Text/Images/Tables and create HTML templates as well.
You can also directly edit the HTML content by choosing HTML editor option.
1. Go to Content --> Site pages and then Create/Edit any Site page.
2. Click on Edit option to proceed with editing
3. Edit or add any information that needs to be done.
4. Copy paste any content that you want to be reflected in the site pages.
6. Click on Save and Upload button after every modifications done in every site pages.