Does an antenna still receive signals without a resonator?
I want to amplify the signal before separating the frequencies out but
  I don’t know if the antenna even receives signals without being
  connected to a resonator.


It does pick up signals without anything connected. An antenna is just an impedance converter from free space (roughly 377 ohms or, put another way, the ratio of electric field to magnetic field strengths are 377:1) to 73 ohms for a dipole (at the right frequency). 


  I want to connect the antenna directly to an analog to digital
  converter to analyze all frequencies mixed together. Is that possible?


It's possible but problematic without a broadband amplifier because an ADC input is fairly noisy compared to the micro volt signal levels produced by a regular antenna. This is why we use tuned circuits - the wealth (if that's the right word) of signals that can be received across a wide range of frequencies needs to be differentiated into the signal we want and that vastly improves signal to noise ratio and means we can amplify the filtered signal without amplifying what we don't want.