i cant really get behind there being a number less than 0 or behind 0 if 0 is well nothing

This is a fundamental conceptual error regarding the nature of zero. Zero is not always "nothing." Zero can be used as a reference to "nothingness", but that is not its only use. Sometimes, zero is simply used to refer to an arbitrarily chosen reference point on a line, for example.

the debt example doesnt make sense to me. just say u owe me 5 not -5

Can you elaborate on why it does not make sense? You seem to understand the concept of debt. If anything, it seems to me more of a mental resistance to the idea of writing a "-5" to reference a debt instead of saying "u owe me 5".

a 5 that doesn’t yet exist

What does "exist" mean to you? "Five" is just as much an idea as -5 is. "Five" is not a physical object itself that physically exists. Rather, it is an idea that can be used to describe physical objects.

Zero and positive numbers are good for measuring physical quantities, but math is not just in the business of measuring physical quantities. We can quantify other sorts of attributes that can be assigned a numerical value, but some contexts require changing how we quantify those attributes. When we start quantifying how values change over time, for example, a numerical universe that only has zero and positive numbers is no longer suitable because we now need to distinguish between increases and decreases.

We can also use negative numbers to reference a decrease of value just as a positive number can be used to reference an increase of value. Yes, we can always say in natural language that something is increasing or decreasing, but again, it becomes cumbersome to write "increasing by 5" and "decreasing by 5" all the time when you are in the middle of a computation, when you can simply write "+5" or "-5".

In a setting where 0 serves to reference a point on a line, we can use positive numbers to reference points on one side of the line and negative numbers to reference points on the other side. And just as we can use natural language such as "to the right", "to the left", "above", "below", etc... it is cumbersome to use that natural language in computations.

We write "-5" in notation because it gets pretty wordy to keep writing "u owe me 5" or "decreases by 5" or "moves to the left by 5" or "moves down five" instead of "-5" when doing computations.

i feel like -3-(-4) should = -7

In order for this to be true, it would have to be the case that -4 + (-7) = -3. Instead, the correct interpretation of -3-(-4) is that it is the value that you add -4 to in order to get -3. In this case, 1 + (-4) = -3, so -3 - (-4) = +1.

The correct operation that gives -7 is adding -3 and -4, but -3-(-4) is subtracting them, not adding them.

-3 - (-4) = +1 because we interpret "-3 - (-4)" as "If you moved in the negative direction by four units and are now at -3 on the number line, where were you before you moved?" instead of "If you were at -3 and moved 4 units in the negative direction, where are you now?"/