It is easiest to recover the data from a backup made before you encountered the problem. Trying to recover data after you encounter a problem is a pain, very difficult, and sometimes even impossible.
The "OSX Base" is the macOS installer. If this is on the physical internal drive, then you may have a major issue since that usually only occurs once a drive has been erased. If an SSD has been erased, then the data on it is permanently destroyed. "OSX Base" is also seen as a virtual volume when booting into Recovery Mode, Internet Recovery Mode, and from a macOS USB installer and can be ignored.
Do not make any modifications to any partitions until you recover your data! Modifying partitions is always risky even if you are not having any problems.
If you can boot into Windows, then maybe you can install the Paragon APFS (or HFS+) drivers (paid utility) to see if you can access the data on the macOS side. I do not know if there are any data recovery apps for Windows that will recover macOS files as that is not typically advertised on the data recovery app's websites. Most apps have a demo or trial mode so you can see if the data recovery app is able to locate anything.
You can also put the Mac into Target Disk Mode and connect it to another Mac to attempt to access the data and to use a data recovery app.
It may be easiest to install macOS to an external USB drive so that you can use a data recovery app to attempt to recover your data. I've used Data Rescue many many years ago, but there are several other good apps available which I've never used such as Stellar and I believe Easeus.
You should always have frequent and regular backups of your computer (each OS & partition) and all external media which contains important & unique data.
