Have a nice day.
That’s like saying that a computer can do calculations on numbers larger than the number of particles in the computer, so where is the calculation happening?. Quantum computers do calculations using quantum states. This process can be described using any of the many interpretations of quantum mechanics. In some of them it isn’t easy to describe, but then, it’s not easy to describe in the Many Worlds interpretation: It’s not a result of doing many different calculations in parallel in different universes.
And yes, you can argue that the Many Worlds interpretation is the “simplest” or “most parsimonious” interpretation. You can also argue that it’s the least parsimonious, because you can’t posit much more than an infinitude of entire universes. You can also argue that any other interpretation you care to name is the most or least parsimonious, because in a very real sense, they all posit exactly the same things. If an argument inherently depends on one interpretation of quantum mechanics over another, that’s a sign that the argument is pure nonsense.
I can see how you may luckily find yourself in a Many Worlds Interpretation branched universe in which you avoid all accidental or intentional deaths and live a long time, but how can you survive in any universe beyond the upper limit of a human lifespan without invoking an afterlife? Don’t all the universes in the MWI have to obey the physical laws of the universe from which they branch? In some branched universes do aging and dying from natural causes not exist? That appears to defy logic.
This PDF paper presents arguments against Quantum Immortality. The ‘Quantum Immortality’ section starting on page 12 seems especially relevant.
Here’s a list of stories using this kind of idea
There’s also Egan’s “The Infinite Assassin”
I’m assuming that you don’t mean the Niven story “All the Myriad Ways”
Interesting philosophical conundrum, but I think it’s a copy, not a continuation of your actual consciousness.
Take a similar common sci-fi trope: copying the contents of your brain to a computer simulation before you die. It’s been done many times, recently ‘Upload’ on Prime video or the ‘San Junipero’ episode of Black Mirror.
The copy will for all intents and purposes ‘be’ you, but ‘you’ will still cease to exist. Your original consciousness won’t travel to the copy made of it.
It’s not a matter of traveling, you are already there.
I just walked up a flight of stairs. In a hopefully small but non-zero number of universes, I tripped and broke my neck. That in this universe I did not does not mean I’m a copy of one who did, it just means that I didn’t.
It’s worse than that. In jillions of split-off universes you walked up those stairs at a slightly different pace. Or stepped in a slightly different spot, or daydreamed about slightly different things.
And in every one of those you are still alive and conscious and all the rest. This all “feels” normal because this is exactly how you and everything else in the Universe has been working since The Beginning.
There are a jillion "you"s each independently considering what to do next. Some scratch their crotch, others choose to post to this thread on the 'Dope, while others go get coffee. And for each nanosecond of their existence, another umpteen jilllion possibilities are born as the entire universe ticks inexorably forward and every particle in that universe spawns a few fresh universes for all the others to participate in.
Said another way, it’s not that at any given moment “anything can happen”; it’s that “everything possible is happening; just separately.” With the “every possibility is manifest in at least one branch” occurring at insanely high frequency times insanely many particles and hence insanely^3 many possibilities.
That’s “Many Worlds”, and the word “many” is as monstrous an anti-exaggeration as the “big” in Big Bang.
[aside]
What is the word for an anti-exaggeration, a term that grossly understates the situation it applies to?
[/aside]
The Universe is big. Lots of stuff happens in it. There’s a good chance you have doppelgangers in the observable Universe and almost certainly in the entire Universe.
Earth is like a flea on the back of a dog…assuming the dog is the size of our solar system.
If the Many-Worlds Interpretation is reality, there are more copies of you than you can shake a stick at.
You should be proud of some of your doppelganger’s accomplishments, you’ve done great things. You, my friend, cured cancer many times!
On the other hand, you should be ashamed of some of your other doppelganger’s deeds. What the heck motivated you to have sex with that panda?!?
I dunno … Maybe 'cuz the sex with the sheep the day before felt soooo good? 
Bi-color is hot!!!
Similar to my questions about time travel (ie “where” is the past or future to travel to), for multiple universes, where would they be? Like do they all overlay each other and you could theoretically travel to different ones by changing some dimensions of your atomic structure or something? Quantum mechanics allows for more dimensions than the 4 we are familiar with. But again, my brain can’t really comprehend what they really means as anything more than artifacts of a mathematical equation.
Because your brain didn’t evolve to think that way, as its only purpose was to keep you alive in order to pass on your weak-ass DNA. 
. Sorry, thought that was funny.
Anyway, this might help; https://m.youtube.com/playlist?list=PLsPUh22kYmNCAR1U8MD_1ELQnl640zYqi
Got it. So a big ball of wibbly-wobbly, timey-wimey… stuff.