Inflation brings value down for a simple reason, but it gets far more complicated in global economies and with currency exchange.
I'll explain the super simple version of inflation:
Imagine you live in one of a small group of disparate communities in a fictional time and/or government (let's say ~10,000 people in total).
You decide to distribute a type of "currency" to exchange items for and put values on them b/c bartering is just such a hassle.
You create a bunch of pieces of paper and call it a "dollar". People can now freely put values on items like salt, sugar, milk, etc and you can simply buy them with any of the monetary "dollars". We don't have to barter anymore.
Let's just say that you decided to print up a bunch of these dollars b/c you owed one of the neighboring communities after they gave you tons of salt, sugar, milk, etc to keep your community afloat. You print up twice as many dollars as were initially in circulation to pay them back.
This will cause inflation and will in essence lower the value of the dollar (in a closed economy - not going to make it complicated with foreign economies & currency rates).
Why? B/c you have twice as many dollars in circulation now. If there are twice as many dollars in circulation then the price of things like milk, sugar, salt, wheat, etc will go up b/c by virtue of printing more money you have lowered its value; people have more dollars now, but things cost more.
That's inflation on a super simple 50,000ft level.
Or imagine if every person you knew had $1000 in their wallet all the time. Imagine there were so many dollars that everyone had that much money just like a person has $1 or $10 in their pocket today. If that were the case why would you do *anything* for say $50? When every person walking around has $1000+ cash in their wallets let alone their bank accounts. You would want way more dollars for any given item or service b/c there are now way more dollars available to everyone. That's inflation.
You can't simply print more money b/c now it just means the price of things have to go up. Consequently this is also why we can't just create a perfect Utopia where everyone makes, say, $50/hr or more.
Why again? Same as above. If everyone had that much money it means the price of things will go up which means those seemingly large salaries are actually worth very little (b/c virtually everyone has that much money now).
Hopefully that helps understand it a little more easily?