If the global debt is currently over 49 trillion, to whom do we owe it to exactly?

To be clear, the $49 trillion figure refers to 'public' debt, ie. government debt. It does not include private debt which is another figure and a separate story. Over the entire world, the fact that every government in the world is in debt means one thing: the world’s private sector is taking a massive amount of money from the world’s governments. Which means its taking a massive amount of money from the world’s taxpayers. Which is what anyone who has been paying any attention whatsoever has come to expect from modern capitalism.

Quite a bit of the money is owed by each country to themselves. For example, as at year 2016 $5 trillion-ish of the US national debt is “intragovernmental,” which is close to a third of our total debt.

The money is owed directly and indirectly to 'savers'. Here are a few (somewhat simplified) examples:
1 Banks. Do you have cash deposited in a bank? Your banks will lend this money out to individuals, corporates and governments. Banks are generally heavy buyers of short term government bills, ie. they lend money to the US government on short term basis.
2 Funds. Have you invested your money in a bond fund or have money in a pension fund (or 401k)? Many bond funds and pension funds are heavy investors in government debt around the world (ie. lend it to different governments around the world).
3 Governments. Governments themselves are one of the largest holders of other governments' debt. For example, Japan and China are large holders of US government bonds. This is where it gets slightly complicated. A government can be both a borrower in one currency (usually its own) and saver in a different currency (usually the US dollar or Euro). A good example is Japan. Due to Japan's trade surplus, it holds a large US dollar foreign currency reserve. It will invest the US dollar in US government bonds (ie. lend it to the US government). However, Japan is a net borrower - it owes more in Yen than it has assets held in other currencies.

The money coming out of the government is NOT NEW MONEY. It’s borrowed and taxed from what I already called the river of debt called the US money supply, which is all borrowed into existence from the private banks as mentioned. The banks create the new money and then remove it when loans are paid. But the money the government uses, as noted earlier, comes from and goes back to that river and so doesn’t really “go” anywhere even though the passage through the government’s capillary causes the debt meter to increment ever upwards.

Does this matter to the common person? Yes, most definitely. A government unable to manage its debt balance will ultimately hurt savers like yourself (assuming you are a saver) and may topple an economy in extreme cases.

Don't forget that most currencies, including the US dollar, are fiat currencies. Fiat currencies are not backed by anything but 'faith' in the government. If the government is unable to repay the debt, it will have to 'print' money. Money printing leads to inflation, which ultimately (albeit slowly) transfers wealth away from the saver to the borrower. In extreme cases, massive printing of money leads to hyperinflation where the currency is 'debased' and rendered near worthless. The average life expectancy of a fiat currency is about 30 years [1]. Don't kid yourself if you think it can never happen to you. The US dollar had to break away from the gold standard in 1971 because it was unable to balance payments and repay debt. We've had it pretty easy, so far.

You may be interested in a side note beyond the topic of this question. Inflation devalues a currency against another currency. It is meant to be economy's natural adjusting mechanism to improve a country's competitiveness. Ie. If the US dollar devalues against the Yen, it will make US goods more competitive relative to Japan. This has some implications:

Countries which control their own currency, such as the US, can print money to repay debt.  In the process, they improve their competitiveness by being able to produce goods relatively cheaper.  Of course, this has to be managed very carefully to avoid the currency going into the debasement death spiral.  Print just enough money to pay some debt, improve competitiveness, maintain confidence and hope economic improvement will take care of the remaining debt.  There is at least a way out.
This is why individual Eurozone members are in trouble.  Greece, for example, does not control the Euro.  They cannot print to repay debt.  They are unable to adjust the competitiveness of their labor force because they are stuck with the Euro.  The Greek government must make deep budget cuts which has repercussions to the broader economy and social confidence.  One alternative is to break away from the Euro and reestablish the Greek Drachma - a draconian measure that tempts fate.  To avoid a default (at least in the short term), Greece will need a German bailout and debt forgiveness.  Does Germany want to go through with this and keep throwing good money after bad?  However, a Greek default will have widespread repercussions across the Eurozone (remember many banks, funds and governments hold Greek government debt).  Does Germany want to risk financial and political contagion?  The Euro is structurally flawed and there are many historical, political and long term economic consequences for Germany (and other Eurozone members) to consider.

The economic fate of many rests on the decisions of a few. This fiasco would be more interesting if it weren't so scary.
The only way to pay the debt off completely is to return to a sovereign currency.