Too many unknown passwords in Keychain...what do to?

You can see what the passwords are by opening Safari.

1. Open Safari, then in the menubar go to "Safari->Preferences"
2. In the window that appears, click the "Passwords" tab
3. Enter your MacOS password
4. Select any website you want to examine. The password will be displayed for that one, selected item.

You can then right-click and copy the password to be entered in the website, or safari should automatically pre-fill the information when the website prompts for it.

I'm not sure I understand what worries you in this context. Safari keeps track of the passwords you use so you don't have to remember them. Plus, when you sign in to a website, or wish to change the password on an existing website, Safari will recommend a very high-strength password character combination and store it for you.

If you don't want to deal with all those entries, you can remove them from the Safari password list by clicking "remove" at the lower-right of the list. It will only remove it from Safari, but that UserID/Password will still be valid for the website from which that was created for. You would still want to log into that website and maybe shut your account down.

The only thing you need to concern yourself with is that you know what your iCloud password is and for obvious reason, do not give that out to anyone.

Delete what you don't think you need.