One should not be trying to learn physics from Wikipedia, particularly not for something as complicated as QM, even more particularly not for an aspect of QM as contentious as the MWI.
The MWI says that there is one single universal wave function, which evolves in time by unitary evolution forever, and that that universal wave function is all that exists. That is one universe, not an infinity of them. It is just one universe that is nothing like what we think we perceive.
Not the parent, but I 'd say this amounts to how you define a "universe". There is a single wavefunction which says that one "copy" of you observes result A and another "copy" observes result B. Using the phrase "many universes" implies that these two scenarios are considered as "different universes". I personally do not like this phrase and find it misleading.
You are all the "copies", and, under certain conditions, can experience all their observations. Think of yourself more as an aspect of a multifaceted being experiencing the universe through you.
Practice lucid dreaming, so you can maintain a semi-awake meditative state. Practice remembering your dreams -some of them are memories from other aspects like you, others are your subconscious communicating through symbols and situations. Practice asking questions, dreaming, and remembering. Practice reaching the semi-awake meditative state from the awakened end of your day. Realize, what you think of as your body, is the 4D sensory organ of your hyperdimensional self, maintain meditative state, and open your other eyes. The effect is a lot like the collage view of regular stereoscopic vision, except out of the immediate overton-window of aspects of yourself similar enough to you.
Getting to that point can take several years. A quicker option seem to be drugs, based on conversations I had with friends, but I never wanted to artificially taint my perception, so I did it the hard way. My findings are that while there is no fate, there exist enough aspects in universes similar enough to yours, but perhaps chronically shifted, that you can learn from their mistakes. This is known as instinct, "guardian angels", premonition, deja-vue, etc.
Good luck.
If you can receive information from alternative universes, experiments can be devised to prove this, and would indeed answer a great many questions in quantum physics. Physicists and others interested in the field would be extremely grateful. As would cogitative scientists and statisticians, who would need to adjust their experimentally demonstrated explanations for instinct, "guardian angels", premonitions, deja-vue etc.
Those worlds are states in superposition, the term "world" is an allegory to help people understand that those states don't interact due to linearity of the Schrodinger equation, because not all properties of linearity are obvious.
Let's say we generally subscribed to the flat earth theory. But that causes many problems with our actual measurements. So someone proposes the "many earths" theory, where there are many flat earths connected at different angles.
If you could travel between these many earths, you could even end up in one - let's call this mythical land "Australia" - where South was up!
Sounds a bit crazy but some people believe it could really exist.
>The many-worlds interpretation implies that there are most likely an uncountably infinite number of universes.
https://en.wikipedia.org/wiki/Many-worlds_interpretation