First lets talk about the resurrection in general. I would recommend using the King Version or maybe the old ASV version.
The old testament concept of the resurrection involves the raising up of the original body that died. (Isaiah 26;19 KJV, ASV see also Daniel 12:2.) Jesus taught that he would raise his own body (John 2:19-20). Jesus also taught that the bodies in the graves come out (John 5:28-29). Paul continues this thought (Romans 8:11, Romans 8:23). So we see that both the old and new testaments teach the resurrection of the original body.
The watchtower disagrees with these plain Bible verses and instead teaches that the body placed in the grave is NOT raised.
"NO BODILY RESURRECTION Besides, nowere in the Scriptures do we read that the bodies of the dead will be raised up; . . . The 'dead,' yes, but not the 'dead bodies.'" Watchtower January 1, 1961 p.29
The watchtower also teaches that Jesus's body was NOT raised But was "disposed of"
On to 1 Corinthians 15:44
Look again at Romans 8:11. Paul is talking about our mortal bodies being resurrected. This is confirmed by Romans 8:23.
Now compare 1 Corinthians 15:53-54 with Romans 8:11. They are talking about the same thing-the resurrection of the original body. So the 15th chapter of 1 Corinthians agrees with the rest of the scriptures previously showing resurrection of the original body (albeit in a glorified state)
What about 1 Corinthians 15:44 then?
1. Most Bible versions render the word as "natural" rather than the NWT,s "physical"
2. The verse is showing that our original bodies will be raised as righteous and sin free. 1 Corinthians 15:44 is comparing the righteous sin free resurrected body with the sinful natural nature of the old body.
3. The same greek words are used in 1 Corinthians 2:14 as in 1Corinthians 15:44. Paul is contrasting the "natural" man with the "spiritual" man. Both men however still have their original fleshly bodies.
I hope that this has helped you, and I also hope that you believe in the scriptural truth of the resurrection of the body, as well as the resurrection of the body of the Lord Jesus which is necessary for salvation (Romans 10:9). Please let me know if I can help.