Many processes are running in the background on MacBook Pro Early 2015.

"Safe Mode" loads only the processes required by macOS: Use safe mode to isolate issues with your Mac.

Open items automatically when you log in on Mac describes how to automatically open apps upon logging in.

Brilance wrote:

MacBook Pro Early 2015 runs many processes. How can I find out which are not nessessary and stop them from loading on startup?

What exactly is the bigger issue you are having?

Micro-managing background processes should not be a concern on your macOS (?)