Featured To whom is this reference applied?

Well, "this" is a rather nebulous term, but I'll go out on a limb here and say that "he" and "Mediator" apply to Christ while "those who are called" applies to those who are called. This seems to follow clearly from the passage. Perhaps you have a more specific question?

 

Yes, of the Jews and the nations. The good tidings of great joy were to all people.

 

The clarification may be in Hebrews 4, which seems to be the hinge on which this sermon swings.
Hebrews 4:2-3,11
For this good news—that God has prepared this rest—has been announced to us just as it was to them. But it did them no good because they didn’t share the faith of those who listened to God. For only we who believe can enter his rest. As for the others, God said, “In my anger I took an oath: ‘They will never enter my place of rest,’” even though this rest has been ready since he made the world.

So let us do our best to enter that rest. But if we disobey God, as the people of Israel did, we will fall.

The covenant of grace is first established with Adam as a promise. It is continued with Abraham and then reiterated with David. It is accomplished with Jesus.

 

Male is female too.