I suppose it's pointless to ask you to read those verses in context. He was telling his appointed ministers, the apostles, to go out and preach the gospel, not every Tom, Dick, Harry, and Jeanie. And just previously, Mary had been directed by an angel at the tomb what to do. It wasn't to preach any gospel. It was to go and tell the apostles.
Too many people preaching their interpretation of the gospel is one sure way to turn people off to the Christian message, sometimes forever.
Umm, the context was for all of us, and that does mean every Tom, Dick, and Harry.
And teaching the world to observe ALL things means ALL things, not just the things that sound nice.