Gatsby, like many other static site generators could be a viable solution, sure. It’s important to note, though, that Gatsby isn’t an alternative to React itself. Your Gatsby site will be build using React, actually. But rather, it’s an alternative to the likes of React-Static and Next.js.
The fundamental principle of a static site generator, like Gatsby, is that your entire site is compiled to static, unchanging files. If you make a change to content, you would recompile your website. This does result in very fast, very efficient websites. But their inherent disadvantage is that you have to rebuild a website to reflect changes to content.
Popular with the Gatsby community are certain headless CMS solutions, like Contentful and Netlify CMS. Personally I have used Netlify CMS the most, and it’s a good solution. And there are others in this space as well. Gatsby has done a great job at encouraging involvement in this space.
But again, your site is compiled to static files. So while you have a CMS, it’s not actually going to be used to serve up new data on the fly. Rather, your data is pulled in at compile time. And you would rebuild upon changing said content. That’s the whole caveat (and benefit) to a solution like Gatsby.
Every tool has its uses. Gatsby may not be a good choice for every use case. But I think you’ll find it’s beneficial to learn. And I’d encourage you to dig in and learn it!