Sasha Jones,
Since there's simply no way from what I've read to get back a Microsoft account that's had the primary alias renamed, deleted and all of the associated verification information changed, I think the primary item of interest at this point should be to try and understand how that happened in order to avoid it in the future.
One obvious way is to never get another Microsoft or any other account, since if you can't determine how it happened, the failure is likely to be repeated. It seems from your list that you had the Microsoft Authenticator installed, but I don't understand listing the "main Authenticator account" and main Microsoft account" separately, since these would typically be the same thing?
Though there have been complex hacks using tokens, I suspect that most personal account hacks are much simpler combinations of a breached, brute forced or phished password along with possibly a less secure verification email from someplace like a cable company or other less secure provider who doesn't offer or simply didn't have 2-factor authentication enabled. The other common method has been gamers who've downloaded either cracks, cheats or mods for games, all of which virtually always contain malware and would have provided a hacker with everything they need to bypass 2-Step (2FA) authentication.
Though I believe Microsoft and Google should have either worked faster to provide more secure methods of authentication and/or worked harder to explain these relatively complex issues to their customers, I do understand why this may not have been possible several months ago, since many of the improvements to these systems weren't available at that time.
So, this isn't an excuse, simply an explanation of reality in hopes that some might spend the time necessary to better protect their own accounts, since the bad actors are no longer script kiddies, but rather nation states who are obviously making big money or getting other value out of acquiring existing accounts, personal or business.
Rob