We don't know your income numbers, of course, because we can't see your private tax data.
However, not only is your income from working taxable, but so is your unemployment.
So, together, the incomes may justify your tax bill.
Of course, there are other possibilities, such as your work was actually self-employment, for which you owe 15.7% self-employment tax on your net income in addition to your income tax.
Without knowing your situation and numbers, we can't say.