Between the announcement of another Spider–Man movie and the release of Endgame, it was so illogical and dumb to think about the existence of Spider-Man in his next sequel of the Spider-Man series and none of the fan-theories succeeded to explain about his re-birth or revival after THANOS killed him using the infinity stones while sweeping out the half of the population of the universe.
Therefore, Endgame is the linkup that solves the mystery behind the existence of Spider-Man in his upcoming movie. Ant-Man through Endgame gave a way to reverse what THANOS did using the infinity stones in the Avengers: Infinity War.
Endgame gave a way to the Avengers to revive the population wiped out by Thanos and Antman brought the key to the Avengers to do it.
Antman was in the Quantum Realm when Thanos was using the infinity stones and he was left intact and this was not less than a miracle that gave a way to reverse the effects of infinity stones.
Dr. Banner and Tony Stark combined with Antman to make the gateway to steal the infinity stones before Thanos gets it and use it to reverse the wipe-out and in the end, they succeeded to reverse the wipe-out and this gave Spider-Man another life and the defined his existence of in the upcoming movie Spider-Man: far from Home.