AMP site generated by third party plugin (AMP for WP), and Google AMP itself is a web technology that have a lot of limitations - you can't use all of your normal elements, plugins and features in AMP pages, only simple content allowed by Google AMP.
What is not supported by AMP:
- AMP does not use any of theme options and theme features that you can see on normal site (AMP is a separate website version optimized for Google Indexation on mobile - your regular visitors does not see it, they see normal responsive site version with theme).
- AMP work independently and separately from theme that you use. Theme only can restyle some AMP elements to match it's design to theme design a little big.
- AMP does not support third party page builders for posts - currently AMP for WP support only Gutenberg and Classic editor. If you have other page builder used for your posts content you need to add alternative simple content for your posts (read more below).
- AMP does not support all third party plugins and their shortcodes added to content.
- AMP does not support custom post types (video, audio, gallery, etc) - you will have regular posts with text content and image thumbnails instead for this posts.
You are not required to use AMP, you can disable it (disable AMP for WP plugin in Plugins) and you will have regular responsive website for all mobile visitors and Google. AMP is modern technology and its not on final stage (its still in development by Google).
How to define alternative content for posts in AMP site
When you edit your post you have special content area at the bottom to define alternative AMP content for this page - you need to use it for your posts, if your normal content don't displayed correctly on AMP, because you used features and third party plugins that don't supported by AMP.
If your site homepage is broken after you enabled AMP for WP:
Check that you don't enabled (disable if enabled) this options in AMP for WP plugin Settings > General:
Homepage and AMP Takeover options must be disabled.