AM in particular is quite intuitive as you can study the modulation visually. IMO it's the "everyone could have invented that" modulation technique.
FM is built on a simple idea, but it has more involved maths.
Analog television signals are way more complex IIRC.
Re: the lib you linked - libs used to deal with radio signals is made by people who have studied signal processing and comm systems formally so you will see lots of jargon and advanced maths like Fourier Analysis. However, you most likely can build something shittier yet working by yourself by understanding the fundamentals of how those signals are encoded, modulated and transmitted.
FM is built on a simple idea, but it has more involved maths.
Analog television signals are way more complex IIRC.
Re: the lib you linked - libs used to deal with radio signals is made by people who have studied signal processing and comm systems formally so you will see lots of jargon and advanced maths like Fourier Analysis. However, you most likely can build something shittier yet working by yourself by understanding the fundamentals of how those signals are encoded, modulated and transmitted.