As anyone who has been watching the Arrowverse should know, the entire tv universe of DC heroes started with the Green Arrow. Oliver Queen became stranded on the island of Liam Yu, returned home, became a vigilante known as the hood, killed a bunch of bad guys, reconciled with family and friends, and stopped a plot by Malcolm Merlynn/ Dark Archer to bulldoze a part of Starlight City known as the Glades. After its first season was a success, Oliver would go on to face foes such as Deathstroke, Damien Dark, a evil version of Laurel Lance known as Black Siren who eventually becomes an ally, and even The Anti Monitor. Oliver was helped by bodyguard John Diggle, tech guy Kurtis, Wilddog aka Rene Rameriz, a bunch of different canaries such as Sara Lance, Laurel Lance, Dinah Drake, and like I said Laurel evil double Black Siren who became an ally, Roy Harper, his sister Thea Queen, and his wife Felicity Smoak.
Toward the end of Arrow, Oliver and Felicity had a baby. A grown up version of the baby, named Mia, was shown in the Arrowverse event Crisis on Infinite Earths. It was here that Oliver era as a hero came to an end. He sacrficed himself so Supergirl and The Flash could live, and billions had enough time to evacuate supergirl earth before it was destroyed by the Anti Monitor. He spoke with the grown up Mia one last time.
This was not the official end of Arrow thought. There was a backdoor pilot starring Mia, Dinah, and Black Siren’s Laurel in the future, Mia had forgotten the events of Crisis, and who she was suppose to be. Black Siren and Dinah come along and remind her who she is. They than go on to save Mia kidnapped friend. This was suppose to set up the Green Arrow and Canries tv series, but sadly the Cw will not be showing this show. Oh well, we survived 2020 after all. Maybe this idea will survive on some other platform like HBO Max.