Assuming you've got 16GB with 15GB in use? Your main culprits are using around 0.5GB, so yeah, 98% (of your remaining 1GB) with all the little tasks sounds about right.
Can you screenshot 'processes' in task manager?
Nothing in your screenshots explains the usage..... so I'd potentially look to viruses/malware.
I would run a scan with Avast, as you have it installed - alongside Malwarebytes and see what they detect.
https://www.malwarebytes.com/premium/