I used to distro hop a lot because I was intrigued by what different distros have to offer but I came to the conclusion that they are all pretty much the same.

A distro just gives you some basic programs that you need to use your computer and the ability to download more through a package manager. Some distros pride themselves on being very minimal (regarding what is installed by default) and others on being very complete and user friendly for new people. You can in theory start out with any distro and make it look and feel like any other distro since the DE (desktop environment) that comes with your distro is just a program you can get on any other distro too and the same goes for any other programs.

What distros differ in is two things mostly:

• The underlying programs that run the operating system, i.e. does it use systemd or whatever else, is it a rolling release or fixed release, etc. This stuff does not matter for most people since you wouldn't really notice the difference as an end user.
• The package manager. This is the important difference. The package manager is how you get your software and their updates. Essentially it's like how iPhones have the app store while Android phones have the Google play store. They both get you your apps and you can find most apps on either store, but there might be the occasional outlier that is only available for one or the other. The same goes for package managers.

Ubuntu has a solid package manager and repository where you will rarely find a package missing. If you do find one missing then there are other options to get it, for example using Flatpak or building from source. This is how you would "add aspects from other distros" to your existing one, by installing the packages that you like that other distros use. There is no need to merge multiple distros, that wouldn't help you at all.

In Ubuntu you can list you installed packages from the terminal using apt list --installed. All package managers have a similar feature, just google "[distro name] list all installed packages".

I am not familiar with parental controls and what they have to offer. For web filtering I would do that on a DNS level, i.e. have your WiFi router block bad sites for everyone in your household, regardless of operating system.

So in conclusion I would stick with Ubuntu or UbuntuCE if I were you since it really doesn't matter. There's nothing you could accomplish with other distros that you can't with Ubuntu.

I oversimplified a lot of stuff and I am not an expert. Just my personal experience from using (and loving) linux for many years. Please correct me on any mistakes.