why do I get chromium updates like in the screenshot when i don't have chromium installed?
Check Installing packages using Synaptic Package Manager GUI to see if you have any Chromium packages installed. If so, remove them and you'll stop getting Chromium updates. If not, then post back here.
The chromium codecs at the top is the thing you are getting updates on.
The rest should stay, I would think.
but what is this codecs? does the system need it?