Just inherited a good computer running Win7 BUT its prior owner did not install any updates for quite a long while. So there is a backlog of 20 uninstalled "important updates." 1 is dated 2014, 16 are 2016, 3 are 2018. Is there a website anywhere that lists the truly TRULY essential (& *safe*) updates for Win7?
If it was me, I would just install every update. It has been my experience, with many different computers, over many years that is very rare for an update to cause any issues. That is why, I just blindly install every update and have never actually taken the time to wait for feedback on updates, so that I could pick and choose, what to install. While it is common to see posts here, about issues with certain updates, in my case, that has been very rare.
Few weeks ago I reinstalled Windows 7 on my friend's computer and I installed all Important and Recommended updates and skipped Optional. I didn't encounter any problems, so that would be my advise also. If you're not sure, you can take system image before you update it.
On Seven I always installed only security updates, except one or two other updates that fixed determined issues - but I don't remember which. Also because in Seven Winsxs grows continually, and I don't see the need to contribute..... never had issues, but I can't say if it is equal for all systems.