As for my explanation of why resurrection is important - I don’t like it also. But it’s the best I got so far. Do hope to find a better one though. My problem was that until I realized that resurrection was a part of the gospel, I didn’t even try hard enough to understand it better.

Regarding your last point, I absolutely agree that the death and resurrection are not the whole gospel - there are so many other implications that can be considered the gospel. If we limit it to death and resurrection, then why did Paul criticize Peter in Galatians 2:14, You are not acting in line with the truth of the gospel. What does forcing Gentiles to obey Jewish customs have to do with the death and resurrection of Jesus? Well, these might not be related directly, but they are related through implications of the death and resurrection. These implications do constitute the gospel, of which death and resurrection is the core.

A good question would be if the Pentecost and ascension can also be considered a part or implication of the gospel, even though they are not explicitly mentioned as such.

I was trying to point out that from the gospel-acts narrative, the resurrection, when considered alone did not give them the courage and power. So, it seems to me to be reductionistic to attribute the courage to proclaim the gospel merely to the resurrection.

Another interesting question to ask would be: yes, Paul did only mention the death and resurrection of Christ as first importance, as the gospel. But then are we to say then that the incarnation and perfect obedience of Jesus as not part of the gospel? Surely, Paul by asking the Corinthians to recall the death and resurrection, he is reminding them of the historical story of Jesus for whom his death and resurrection is central.

Perhaps the main problem I have is that Paul wasn’t mentioning the death and resurrection merely in terms of abstract, theological categories (though there are certainly theological implications!)

I think equally important would be Christ’s ascension which doesn’t feature much as well. Although it is not understandable how Christ really ascended, the fact that it is a bodily ascension is noteworthy i.e. Christ is not alive now as an disembodied soul.

And it should be important to note that Peter, John and the rest did not obtain courage from the resurrection event alone. The Pentecost featured is quite important as well.

Of course, the problem is not really that we do not emphasize this or that event enough. We should think of all the events in a connected fashion. Death -> resurrection -> ascension -> pentecost. Maybe the really problem is our itsy bitsiness.