When trying out the new layout builder I have to say that the mixture of header, footer and content is not a nice solution for me.
It is still quite clear if you only have a header, footer and then maybe a layout for all pages and one for archives. But on my larger pages that quickly becomes confusing when the headers and footers are lost in the other layouts. There is also visually no distinction, everything looks the same. The only possibility to filter something is via the search function, which can be annoying in the long run.
I ask you to reconsider this. Header and Footer are special layouts and should be easy to find. If everything should be found under the layout builder, then you could also display the different areas differently, such as separated in columns. (Header, Footer, Pages, Archives).
That would already contribute a lot to the handling help.
I could imagine something like this: