I used to be a Field Economist for the United States Department of Labor and I researched inflation which is the devaluation of money. The United States government controls the value of money in two ways.

The first is through monetary policy and that one is controlled by the Federal Reserve Bank.

The second is fiscal policy and that one is controlled by congress. The 900bn relief package that you are writing about is through congress and I expect there will be another one in excess of 1 trillion in a couple of months.

I separate monetary and fiscal because the net effect is slightly different. The Federal reserve monetary policy has led to inflation of investment assets. That is why stocks, bonds, gold, crypto, real estate, oil, and other commodities are all rising.

At the same time the job market in the United States has not recovered and the consumer price index is still low, so consumer inflation is low. Now enters fiscal policy.

The relief package (fiscal policy) can cause consumer prices to go up slightly as more of that money will go into the hands of people who will spend it through unemployment benefits. Some of it will be saved though. There is some data that suggest that some of this money will be saved and some of this stimulus will go towards more equity purchases.

In this case there will not be a large effect on inflation for consumer prices, but you will see some uptick in asset prices. This is just the demand side--spending.

On the supply side you do see commodity prices rising which implies that there will be an uptick of manufacturing. As long as you are creating goods faster than people are spending money then that would also limit inflation.

As for the effects of inflation on people. Inflation is the devaluation of money. If the Dollar or the Euro is lowing value then you are harmed if you hold Dollars or Euros. The more you hold the more it hurts. However, the opposite is true if you are poor and you are in debt.

If you hold no money or you are in debt inflation is helpful because you get to pay back your loans with money that is less valuable then when you borrowed it. Also, as a side effect the inflation that is driven by extra dollars being in the market also creates jobs. There is an inverse relationship between liquidity and unemployment in most of the data.

As for your question on what non US central banks should do? That is going to be dependent on the current state of each of those countries. The United States can print money almost indefinitely because it is currently the reserve currency of the world, but everybody else is limited in how much money they can print. I won't go too much further into this as my comment is already too long. If anybody wants to know more about this they can reach out to me.