The "Minetest" you tried was likely just the barebones example game that used to ship with the engine. Since so many people got confused by that, they stopped distributing that example game with the engine and now you get asked what fully featured games you want on first start. Voxelibre is the one that is like Minecraft but better.

I tried minetest long ago and was not particularly impressed.

Until a the last couole of years, it wasn't terribly impressive. It is, now.

Has the community grown big enough?

That's a tough question. Minecraft is 3 of the 10 most poplar games of all time. (Measuring every version of Minecraft separately, several versions will crack most "Top 10" lists.)

So compared to Minecraft, the Luanti community is tiny.

But compared to other Indie games, it feels like Luanti is huge now.