Robert, I would say that it helps to know Jesus, and what He said and did, in order to know the right way to live according to God. It saves us a lot of pain and grief in the long run if we should trust and live by His word. But even many who know the word of God ( the elect) are deceived or perhaps they fall asleep at the wheel per say. There are other ways in which we may come to know the truth. As Romans 1:19 says : " because what may be known of God is manifest in them, for God has shown it to them." God has given us a heart and a mind, as well as eyes and ears. Again, as Romans 2:15 states, the conscience bears witness, as well as the works that we do (John 5:36). If the things that we do are not bringing joy, happiness, prosperity, etc. to our lives or the lives of others but instead are causing pain, destruction, etc. and wreaking havoc, then this is an indication that our ways are not good. We know how it feels when someone treats us badly. Why would we do this to someone else? Other people can also give testimony. Those that have “been there, done that” can tell you their stories whether to the good or bad. Observing how others live, for example-the life of an alcoholic, drug addict, etc., reveals a lot.
In answer to your other questions, I think one of the reasons God came to earth was to show us the right path by way of example, to make it simple and easy to understand. I don’t think God ever expected us to be perfect. There is only One who is perfect and that is God Himself. But, yes we can follow what Jesus said and did, for He told us to do so ( Matthew 28: 19-20). This is righteousness, according to God, for us as humans.