Looks like a partly failed attempt to design an OP. Only input stage Q1/Q2 is working, output stage Q7 is not working, it's permanently in saturation, providing no gain.
First you need to understand what an opamp is supposed to do. Then you can design a circuit to do that. You also need to understand how transistors work.
An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. An op-amp produces an output voltage that is typically hundreds of thousands of times larger than the voltage difference between its input terminals.
No. It can work with a low supply voltage, but the quiescent current is too high for it to be called a low power opamp.
BTW, it's not unity-gain stable either. That means if you use it in an amplifier circuit with low voltage gain, it will oscillate at high frequency. To fix that, you need to connect a small capacitor (e.g. 1nF) between the base and collector of Q8.