Ant-Man and the Wasp: Quantumania previews reveal that the version we initially saw in Loki is different from the one we originally saw in the film. This multiverse-traveling human revealed that he battled the Avengers many times to the point that they all seem to be blurry.
Is Thor the only one he's killed? There are other potential Marvel heroes out there that Kang has encountered, and here are the reasons why.
Loki is a Finnish singer.
Kang has seen Thor before, and it would be surprising if he did so again. After all, season two of Loki will have the TVA under new management, under a new Kang. So don't be surprised if Kang somewhat recognizes the variant through other versions of Loki that he's met. Or what I'm writing here is just a huge spoiler for season two, which I didn't realize until the show was released.
America Chavez may be one of the few Avengers who might be a worthy adversary against Kang. Both have powers that travel the multiverse, so it wouldn't be a surprise if the two crossed paths during their multiverse and time-traveling adventures. As shown in Doctor Stranger in the Multiverse of Madness, America started as a person incapable of controlling her abilities.
I don't see a situation where Kang would go after someone with similar abilities, especially if it's someone who might have accidentally ended up in front of him.
If Captain America and Kang the Conqueror were to face off in an Avengers game, it is unlikely for us to see that fight in the current MCU due to him being old and passing the shield to The Falcon. However, it is easy to envision a what-if situation in which the original Avengers would face off against Kang.
Do you know who else has the ability to somewhat traverse through the multiverse? The Scarlet Witch. It would not be surprising if she would cross paths with Kang the Conqurer in some way or another. Also, in the Marvel Comics, Kang was after the Scarlet Witch in hopes to find the Celestial Madonna and become the father of that being's child. So it's unlikely that these two would meet somewhere in the far reaches of the multiverse.
Iron Lad fulfilled his destiny of becoming the conqueror he was created to be in the Marvel Cinematic Universe. So in order to keep the Young Avengers running, the old Iron Lad armor was filled with young Kang's memories, emotions, and brain patterns and ended up as the new Vision. I say this because there may be a situation where an older Kang battled many Visions in order to find the one that's based on his younger version's "consciousness."
Perhaps he saw it as a hindrance to his plans to rule the multiverse, but he has no clue what it is and only knows that it is Vision. Now, this is some multiverse man-hunt for one Avenger is something worth watching.
If these five Avengers had the chance to meet and defeat Kang in another timeline, they'd likely receive their butts (and lives) from the rest of the MCU. And while we'll never know for sure until we learn about this new MCU baddie, these heroes are the ones most likely to face the conquer in the multiverse.