” How about gentiles, who have souls and can gain access to Olam Haba?”
Gentiles and Jews have different roles, different levels of responsibility and accountability, and correspondingly, different privileges as well.
Jews are accountable to make the world a G-dly place. We have to live up to higher standards to do that and are held accountable if we don’t. Gentiles are accountable to make the world a functional and moral society (which is a necessary prerequisite for the Jews role.)
As fit for their role, Jews were granted an immortal and G-dly soul which affects their continuum as a nation, and as
individuals. Gentiles have a soul formed in the “image of G-d” but not G-dly or immortal to the same extent as the Jewish soul.
We see this physically and spiritually, already now. Physically, there are many ancient nations which are long gone, whereas the Jews, against all odds, are still around and always will be.
Spiritually, since non Jews were granted the element of free choice with regards to their 7 commands, they can earn olam haba, spiritual afterlife, as well, but not to the same extent as Jews.
With regards to the finish line as you put it, in moshiachs times, there will be nations around, and those nations will serve Hashem, as foretold in many nevuos, amongst them, “Then I will turn over to the nations a refined language to all call out in the Name of Hashem…” “And the nations will flock to it (the Holy Temple.)”
However, afaik, individual resurrection and immortality only applies to the Jews as a nation, and as individuals.