Slowly over time you learn what you need when you need it. There is no hand holding. Under the surface, this thing is very complex. Every aspect of Linux is public. You do not need to understand most of it, but this is the realm of many brilliant developers and most computer science students, especially those studying operating systems. Everyone is welcome here, but be aware that all levels are present.

The vast majority of Linux is not related to desktop users. Linux is more common on servers and embedded devices like routers, cars, and industrial/enterprise equipment. People are happy to help you learn when you hit a wall, but no one wants to be your tech support.

Distros are not brands or marketing. They all have a specific reason to exist and specialties. Learning what these specialties are and how to leverage them for things like documentation for any specific task can make a big difference in your overall experience.

It is quite common for people to call it Linux, but you are unlikely to interact with kernel space very much. Your actual experience is mostly limited to the desktop environment and applications.

Since you are on a Debian > Ubuntu derivative, you are on a distro that may have outdated dependencies in some cases, especially with outlier software. Terms like outdated and stable/unstable are not at all what they seem at first intuitive thought. Windows is a stable OS, which really means it has outdated dependencies in most cases too. Distros like Fedora or Arch are kept up to date with the latest kernel and dependencies. If your software you want to run is actively developed and kept up to date, these are the best distros to run. If your software is static, these distros may break it and create headaches. By contrast, if your software is kept up to date but you are on a stable distro, either the distro packager may keep the needed libraries up to date or you need to go to the extra effort required to update stuff yourself by adding a PPA to your Aptitude sources list. This is important to understand because, if you are following documentation for some package using the internet, that documentation may be for a much newer version than what is available in the distro natively. This mostly applies to edgy software when you're doing something specific that is not super common. The practical way to think about this is that Debian stable is primarily created as a way for developers to create some device that will be used online for a specific task and uses many high level software packages. Once the thing is working, the developer knows that the packages they used are not going to get updated arbitrarily and break what they created, while the device is still going to receive all the needed security updates to remain online safely for as long as the kernel is supported by the Debian team. This is beneficial for small one off devices and subcontracted types of development without a full time dev. Understanding this paradigm will massively improve your overall experience. I had a lot of frustration before I understood that much of what I was using was outdated and why when I first started using Ubuntu over 10 years ago.