DMS isn't a child theme, a child theme can not work independently, it has to have a parent theme. DMS is a Design Management System that supports child themes.
The purpose of child themes is that they inherit the functionality of the parent theme in our case DMS. What this means is that, you do not have to edit the core files of DMS, this is something we do not recommend and will void all support if you proceed.
This child theme system isn't something only DMS utilizes, this system is used vigorously throughout Wordpress, nearly all themes support child themes. For more information on child themes see the Wordpress Codex - https://codex.wordpr...rg/Child_Themes
You can create your own child theme, use a third party one such as Nicks Base Theme or you can use my skeleton child theme from my GitHub. It contains nothing except the bare bone files. However, you can copy the sections folder and LESS folder to give you much more control over how your child theme works.
or use the DMS Custom > Custom Scripts via the DMS Toolbar.
If you come from a background of developing websites from static files i.e. having to include the header and footer for each page you create, using Wordpress and DMS will likely be a culture shock to you, as this is not needed. The inclusion of the header and footer are done automatically for you, that's why when you want to add new scripts you will want to enqueue via functions.php file in your child theme or using the DMS Custom Scripts option area.
In regards to adding jQuery, this is not needed as Wordpress already includes it.