How Compounding Works
Compounding means you earn growth on your earlier growth, not just on the money you put in. In the early years most of the balance is your own contributions. Over long periods the growth part takes over, which is why time matters more than the exact starting amount.
The rate does the rest. Try the same figures at 2% and at 5% and compare year 20. Then remember that a higher assumed rate usually means taking more risk, and no rate you type here is promised by anyone.
Inflation works the other way. A dollar in 20 years buys less than a dollar today. The "today's dollars" figure strips out the inflation you assume, so you can compare the result with prices you know now.