Our cells will die when we die. Most of our cells have no future, but the ones that become our children and recombine with somebody of the opposite sex do have a future.
That doesn’t mean the rest of our cells don’t exist in a state of genetic indifference. They have evolutionary pressure to improve the fitness of the individual, otherwise it’s a dead end for all genes involved.
Competition between reproductively capable individuals is different. An ant that acts selfishly will reduce the fitness of the hive with no genetic reward. It’s a losing strategy. But in a society, a selfish person can reap the rewards while taking advantage or damaging the society they belong to.
The fact that humans exhibit behaviors like self sacrifice and loyalty points towards the idea that humans’ evolutionary strategy is somewhat mixed. Selfishness and selflessness coexist because our fitness is to some extend, dependent on the society, or to the hand that feeds us.