The new update with a customized theme

I customized the following files on my site:

includes/theme-interface.php
includes/theme-functions.php
includes/widgets/widget-ajax-posts-by-category.php
content-single.php
style.css

…and today I got an email about the theme being updated. I haven’t worked with child themes before so I’m not really clear on how to go about making the changes that I did work as a child theme? Can I just copy these changed files and their structure over to the child theme folder and then update the main theme? If not, how would I go about doing it?

The main reasons for the changes were to add color to the read more button, remove the clock icon and date for the posts/hero banner and remove the view count and the eye icon from the hero banner, posts and the side panels.

Thank you in advance-