Creating lots of pages from a template

I have around 300 pages with similar structure. They have identical layout but the content inside the paragraphs is different. For instance, all the pages have a structure like:

<h1>Intro</h1>
<p>changing content</p>
<h2>Section 1</h2>
<p>changing content</p>
<h2>Section 2</h2>
<p>changing content</p>
<h2>Section 3</h2>
<p>changing content</p>

All the pages have the same <h1> and <h2> tags, but have different content in the <p> tags.

Unfortunately, the structure of the pages changes often but the content stays the same, so I’d like to find a way to have the structure in a template (or something), and enter the “changing content” on the individual edit post pages.

Here are a few of my ideas, from least to most easy:
– use a database to store the content. I haven’t used databases and this just leaves me with a lot of questions.
– create a template and somehow specify the content on each page’s edit page.
– create a template and create a custom edit page with forms for each section that I want to customize. This sounds like the easiest way but I haven’t seen any examples of this being done.

Can anyone give me any tips to get me started? I’d really appreciate your help.