Can't update my El Capitan install

For the past few months I haven't been able to update my El Capitan install (and other system updates). There remains a persistent 10.11.6 update that it tries to get me to download, but fails, probably because I'm already at 10.11.6

https://imgur.com/a/jHLrf

(as you can see I'm able to receive/download Safari updates)

Does anyone have a fix for this or have a way that I can download and install the latest updates manually?

submitted by /u/deerseason
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