I, too, didn't play minecraft up until this June. My last experience with it was in 2010 with its alpha build where you could just place and mine blocks. For me, Java is the ultimate experience and the easiest to set up for multiplayer. I play in my local LAN with my brother, both running Windows 10 machines and Java x64bit edition.
Because I wanted to have something more of a multiplayer experience, I didn't rely on the native server, but went for an external dedicated server named SpigotMC. It's one of the many forks of craftbukkit, which is an external framework for hosting minecraft. It's just a java executable you have to run in the background on a machine to act as a dedicated server. Because the server is extremely lightweight and Minecraft itself is quite light, I use my potato (5 year-old crappy) machine as both the dedicated server and for playing (I start the server, minimize it, then start the game and connect to the localhost through direct connect). What those external servers add for the experience, are the plugins which make the game extremely enjoyable (RPG progression like Skyrim, easy manipulation of gameplay elements like enchanting, smithing, etc, useful things like adding name tags to things so you know what is dropped, etc).
On top of that, since Minecraft might look a bit blocky/plain to some people, there are some graphic packs and shader packs you can drag and drop in a folder and activated in-game which make the game completely different to the advertised screenshots. Nothing more than eye-candy, but it's there (see attached screenshot for an example). With my potato pc and running the server on it simultaneously as playing the game, I get consistent FPS even with the graphic additions.
As for starting out, the game explains itself as you do things. It gets kinda complicated for the smithing/enchanting/advanced crafting for a young kid, but nothing too serious a family can enjoy. You could very well skip all the RPG stuff and stick to the construction/management of a settlement or house. For me, my best Minecraft moments weren't adventuring, they were just fishing or tending to my garden and farm relaxing after a stress day.
STALKER: Anomaly or STALKER:Call of Chernobyl are probably the only free games I've invested more than 500 hours in. Albeit they are mods of Stalker:Call of Pripyat, they are standalone by themselves.
Other than that, any and all free games out there (including popular ones like Path of Exile) sooner or later end up with paywalls, shading trading business within the game or boring after the first few hours (e.g. I got bored with Team Fortress 2 after 40 hours).
But I have to ask though: Can't you see a review, download a demo or just plain watch a gameplay video of a game to get the gist of it before you buy it? What makes the purchase of a game always being regrettable? I've bought way too many games on GOG and never regretted a single thing I've bought.