All but 9k is student loans, the 9k being a car payment. All of our interest rates are low, we paid off all credit card debt (wasn't really a lot to begin with) and established a solid emergency fund in the beginning. Before I found the FIRE community we did have pretty solid financial sense, not carrying high balances, having some money in savings, being frugal, etc. But this community really kicked things into high gear.
The rate of return of our investments compared to interest rates didn't really factor into our decision as much, we wanted to get started with as much as possible, as early as possible. For my job I can't retire for another 18 years regardless of how much money we save, so as long as my debts are gone by then, growing our investments is more important to us.
This is not to say we are not throwing a large amount of money at our debt, because we are. Almost 25% of our total after tax budget goes towards our debt reduction. We are simply not focused on growing that number vs growing the 40% savings rate we currently are at.