The Fed has to target something. Ideally it would be 0% inflation meaning no deflation or inflation, but it is an imperfect game with imperfect tools, which is why it targets 2%- because if actual inflation falls lower than the target it hopefully still falls at or above 0%. Deflation is arguably much worse than inflation, especially low inflation, in what it does to the economy. Depending on what one believes in this could be a deflationary spiral or monetary policy that is too tight and could stall the economy as it did during the Great Depression. Those cases aside, if there is generally an inverse relationship between unemployment and inflation, then deflation could mean higher unemployment.
When you think of the role of money most people think it should just be a means of exchange and a store of value, not an investment vehicle. For that you would want a 0% inflation rate. But when the tools can't perfectly get you that, you have the risk of having below 0% inflation and greater than 0% inflation month to month or whenever you are gauging inflation. If greater than 0% is the better evil of the two, it might make sense to target an inflation rate above 0%. And that is why we target a 2% inflation rate.
The government doesn't really print money to pay debt. It sells treasury bonds. It is when the Fed buys those bonds with newly made money that you might see it that way. Except that the Fed has not done this historically and even now it is meant to be temporary in that they will eventually sell those treasuries (or most of them) which will mean a "destruction" of money as the treasuries enter the market and the dollars leave it.
