Colored and rainbow crystal cores aren't essential in the early stages of superhuman development, as normal crystal cores are sufficient for leveling up at first. However, as superhumans advance, it becomes increasingly difficult to progress and break through bottlenecks to reach higher levels. At that point, colored and rainbow crystal cores become invaluable, providing the extra power needed to overcome those barriers and achieve significant growth.
To break through these bottlenecks, superhumans not only need to be extremely lucky but also possess significant potential. Additionally, they require a substantial amount of colored crystal cores that align with their specific ability. Without these, progressing to higher levels becomes nearly impossible.