Kang the Conqueror, Explained: Everything We Know After Ant-Man & The Wasp Quantumania

gamespot.com:

While the man who would become Kang the Conqueror was first introduced in Loki Season 1, it's only now, with Ant-Man & the Wasp: Quantumania, that he's taking his rightful place at the center of the Marvel Cinematic Universe for at least the next several years.

Warning! This article contains major spoilers for Ant-Man & the Wasp: Quantumania and other recent entries in the Marvel Cinematic Universe.

Thanos may be a tough act for any cosmic villain to follow, but Kang the Conqueror is more than equipped to do so. This guy's very existence is essentially impossible for us mortals to comprehend because he's so old that he's transcended time. And there are so, so many of him.

This is in stark contrast with Thanos, who was pretty much just a really strong boss alien who punched people who opposed him, and who killed half of all life in our universe using the Infinity Stones. Kang is trillions of years old and has actually destroyed countless entire universes using his own technology that he both invented and built himself. And, again, there are a lot of him. This is a whole new level of problem, and it's going to require plenty of explanation.

At the end of Loki Season 1, we met a character played by Jonathan Majors who was referred to as He Who Remains. This was not Kang, but rather a man named Nathaniel Richards--yes, he's a descendant of Reed Richards of the Fantastic Four. He told Loki and Sylvie that he was a scientist from the 31st Century who discovered the multiverse and soon met alternate versions of himself from other realities. A lot of those other hims were good--many others were not. War happened, and He Who Remains ended it, killing every other version of himself and stabilizing his world with a single timeline