Add Content to Page without shortcodes

This is an interesting question, though a bit too broad for a Q&A model. Here is what I would do:

1. Create a custom post type, where each post is a block of content
2. Create a second custom post type for pages that are assembled from blocks of code. In stead of a content field, create ten drop down fields (or more if there are more blocks possible on a page). For the select options in the dropdown, take the title of all posts in the first custom post type. In this way any new block of content will automatically become available for assembly.
3. Create a template for the second post type, that loops through all drop down fields and assembles the content from the first custom posts.