My budget is ~500 Euro.

I haven’t built a PC in 10 years, I gave no idea where to start.

It will mostly be used to run Nextcloud, Minecraft Server and some future homelab projects.

I’m thinking of using this for the case https://www.the-diy-life.com/introducing-lab-rax-a-3d-printable-modular-10-rack-system

Where do I start? What CPU or motherboard would you recommend? I want it to be somewhat future proof and also act as a NAS