Copy - paste works exactly like any other place.
Right click on the section - copy
Left click where you want to paste it.
The only thing is that you can’t copy more than 1 item at once
Still doesn’t allow me to paste : https://cl.ly/86faf7f34ec7
You can not paste a Section within a Section.
Divs can go one inside another.
Sections, Containers and Link blocks can not be one inside another.
To reiterate what @Eli11 said - paste your section into your body not inside another question
A lot of times I copy/paste my sections like that into the tree view body and then move it via dragging where I want it. Always seems to work that way.