How to get meaningful insights from IQ data saved as binary file?
Depends on what you might find insightful or meaningful.
One common thing, for some visual insight, is to chop the file into suitable sized chunks/windows and feed those IQ data chunks/windows as complex input to an FFT. If you know the RTL-SDR sample rate and frequency settings, then you can use the FFT output to plot a frequency magnitude spectrum, or you can color a sequence of FFT spectrum magnitudes as slices of a waterfall. This allows a visual inspection to see if any signal(s) rise above the noise floor, their frequency offset and bandwidth, and perhaps the visual pattern might look like some known modulation type.
It helps to know the IQ file data format, which for rtl_sdr file capture, is not floating point, but 8-bit offset integer.