As the Avengers neared the end of the Infinity War against Thanos, instead of them winning, Thanos had one last idea to reset the Marvel Universe and remaking everything, but by doing so he died as well. By snapping his fingers, he erased all of the Avengers and Villains from existence, but ended up creating new ones to take their place with similar powers, abilities, and mindsets. This has opened up new possibilities for the Avengers and Villains, with a flood of new powers and versions of old Marvel characters. Some of these characters retain the same last names and abilities as the old Avengers and Villains, but they bring new powers to the fight of the Heroes vs Villains. The new counterparts of the old heroes are younger than before, so the Avengers haven't been established yet.