Copy already edited theme into child-theme?

Heyho,

I'm quite new to WordPress and didn't really know how child-themes work at first. As I was trying to setup a shop and wanted to edit the shop-page layout etc. I stumbled upon the info, that it's probably best to create a child theme first.
The problem is, that I've already changed a lot about the pages overall design via additional CSS and adding classes to specific block as well as creating new paragraphs, pics, navigation elements, etc. in the header & footer. I've changed colors, button designs, etc.
I have now created a new child theme that is supposed to inherit everything from the original Twentytwentyfour theme, but of course it reverts back to it's default settings when I activate it. So all my colors are gone, all the changes I made to my header and footer are gone, etc.
So naturally my question is: is there away to copy everything I edited into my newly created child-theme (I image there must be, as it has to be some files saved somewhere) and if it is, how would I go about that? Ideally that would mean that I could switch to my child-theme and go on exactly where I left off. This surely must be possible right? I wasn't able to find anything about it on the internet, though.

Thanks so much for your help,
BerlinStold