Looking at the original question of this thread, seems to me that it is a question as to whther resurrection is physical or spiritual.
The idea that 1 Cor. 15:20 is generally interpreted as a spiritual resurrection is not correct in the first place, in my opinion.
As "in Adam all died"(spiritually AND physically) so also "in Christ shall all be made alive".
As Seth pointed out, "so also" meaning, in the same way and to the same extent and in the full scope.
The resurrection spoken of begins we we get "in Christ", by grace through faith, a tru confession of the lips acknowledging Jesus as Lord, and a belief that Jesus was resurrected from the dead- spiritually and physically.
Romans 8 declares the consummation of our sonship to be the resurrection of our bodies, but this is not the point of resurrection, it is the result of a resurrection seed sown in the heart(spiritual resurrection) when we believe and submit.
Paul declared the physical resurrection of Jesus Christ, and the resulting freedom from death and resurection of the body for all men in all his writings and everywhere he preached.
Before the Sanhedrin, where the Pharisees and Saducees disagreed about physical resurrection, "I am on trial for the resurrection of the dead".
In Athens at the Aereopagus, "When they heard about the resurrection of the dead some of them sneered, but others said, "We want to hear you again on this subject".
To the Romans, "Not only the creation, but we ourselves also who have the firstfruits of the spirit, groan inwardly awaiting our adoption to sonship, the redemption of our bodies", and, "If we have been united with him in a death like his we shal be united with him in a resurrection like his", then explaing further, "If the Spirit that raised Jesus from the dead dwells in you, He that raised Jesus Christ from the dead will also quicken YOUR MORTAL BODY BY HIS SPIRIT THAT DWELLS IN YOU."
First the spiritual resurrection, then, at the culmination of our deliverance, physical resurrection as a part of the FULL BLOSSOM of spiritual resurrection- they are inseparable.
In 1 Corinthians 15, as with the rest of the New Testament, spiritual resurrection and physical resurrection are ONE. Two sides of one coin, and inextricable from one another as well as inextricable from THE GOSPEL.
The apostles called themselves "witnesses of His resurrection". Without the physical resurrection there is no gospel, it was a core part of the message.