Hi thistlillo75, I am Paulo and I'd like to help.
Sorry to hear you're having this inconvenience navigating this new design. Unfortunately, the creation of folders in "Home" is not allowed as it is only for viewing recent and favorite files and accessing the libraries so the New button (circled + sign you described) there will be grayed out.
To access your files and folders more seamlessly, you can right-click on an empty space on the navigation pane and select "Show all folders". That should give you access to your personal files and create new folders more easily.
You can also set This PC instead of Home to open as default when you launch the File Explorer if that's what you prefer. Just click the three dots > Options > Open File explorer to: and set This PC.
But there will still be changes and fixes in future updates so it is better to give your feedback on this using the Feedback Hub app. :)