pfftkcfffpforfuksake
But, in all seriousness, bronze 5 is lower than bronze 1. As you rank up, you will reach bronze 4, then 3... all the way to 1. Then you will be promoted to silver, following the same number process. Here are the ranks:
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As you win, you gain something called LP, or League Points. You generally start at 0 and build your LP up with wins until you reach 100 points. Wins give you LP, and losses take LP away. Once you reach 100 LP, you'll enter a promotional series which will require you to win a set of games, 2 out of 3. If you win these matches, you will enter the next rank, in your case, bronze 4. If you fail, you will have to attempt 100lp again and restart at a certain lp based on your performance. However, re-entering a series a second time will grant you one free win toward your rank up during your promos.
When you hit bronze 1, or any normal rank with "1" in it, and attain 100lp, your promos will be best 3 out of 5, instead of 2 out of 3. The one free win still applies.
The only exception to this is Master and Challenger rank, which aren't composed of 5 divisions, rather are standalone ranks.
There are some other left out details, but in a nutshell, that's how it works. Good luck, have fun. And may your dreams not be memes.