It should not be necessary to use iTunes for anything file related these days. The Files app gives you access to both the local storage and most cloud or network storage solutions. You can add shared folder from your PC to the iPad in the Files app. This includes high level folders with multiple subfolders, like your user folder on the PC.
To do this share the folder on your PC, and make note of it’s address. Go to Files on the iPad, tap the (…) icon and add a server. Use the address you found on the PC.
The iPad User Guide covers the basics of the Files app fairly well. You can find it in eBook format in the iBooks store (for free), or view the web version here:
Apple - Support - Manuals
There used to be a PDF version. I haven’t seen a link to it in a while. but I wouldn’t be surprised if a bit of searching showed one up.
Be sure to get the right manual for you current iPadOS version.
I’m sure there are more comprehensive books, and maybe one of the other forum members can recommend one. I’ve found the user guide sufficient, along with a little exploration and experimentation.
There are other ways to share files between you iPad and computer. Many document/PDF apps include the ability to transfer files via the PC’s web browser. Instructions on how to use it vary by app, but are usually clearly layed out when you choose that option. In Documents by Readdle the option is Computer, and it tells you what address to enter in the PC’s browser, and supplies a security code to make sure no random person is accessing that address.
I prefer using iCloud, OneDrive, and Google Drive (in that order of preference). iCloud is easy to use on all my Apple products, and I trust the security. OneDrive is easier for my Microsoft apps and my only Windows device. Google is the option when my Google Headed friends need me to share files or workflows. That’s pretty rare these days.