Low Memory on MacBook Air

This is a two part question, one on the Storage capacity of my SSD, and second on the RAM of my computer.

Part one

• My 2015 MacBook Air has been having some storage problems, I use iCloud, and Google storage to save room but the amount of storage that my computer calculates as system files seems quite high (see photo)
• Is there something going on here? How can I diagnose this problem

Part two*

• I know that 4 GB of RAM doesn't give much wiggle room for running lots of applications, but kernal_task seems to take up much of the RAM usage, is this normal (see below) *p.s. I know chrome is the worst thing in the world for RAM*

I'm interested to see some solutions to these problems

Thanks 🙂