Solved: Please note that this it a conflict with woocommerce. After I disabled woocommerce plugin I was able to save changes in Elementor post/page. I then re-enabled woocommerce and the site worked.
Yes, I think that a widget could help. Say I want to configure boxes under the main content of the page or post. But, I don’t want a random or most recent post to come up but rather have it show a specific post or page.