All of these people were still living by faith when they died. They didn’t receive the things God had promised; they only saw them and welcomed them from a long way off. They admitted that they were outsiders and strangers on earth.
The prophets were shown that they weren’t serving themselves. Instead, they were serving you when they spoke about the things that you’ve now heard from those who preached the good news to you with the help of the Holy Spirit sent from heaven. Even angels long to look into these things.
That’s why Christ is the mediator of a new covenant. Now the people that God has called to himself can receive the eternal gift he promised. They can receive it because Christ has died to pay the price and set them free from the sins they committed under the first covenant.