https://projects.raspberrypi.org/en

Just put android on it. Games and tv and user friendly.

So what is an easy to use or no think thing I could use a pi 5 for?

It sounds like you really want something that works "out of the box," in which case, I would look for projects that have disk images available.

This severely restricts what you can do with it, and as others have mentioned, is a bit antithetical to the Pi's original purpose as a tinkering machine. But you may find something you like.

The most basic would be to just use it as a desktop replacement.

Install docker.

Terraria, Starbound, and Valheim all are less resource intensive than Minecraft.

Raspberry Pis are sort of purpose-built to be tinker toys. Low effort push button solutions are not what the designers had in mind, so even easy projects require a little work.

Does Minecraft server have a known memory leak or something?

As a hack you can always set up a cronjob to automatically reboot at a time when you won't be using it, but not sure if that defeats the purpose of a Minecraft server...