Shannon versus Nyquist bit rate calculations
The formulas are not calculating the same thing.  The Nyquist bit rate formula is for a noiseless channel and calculates the maximum bit rate for a given channel bandwidth and number of signaling levels.  Note that the formula uses the number of signal levels, not the actual levels.  It simply combines the bandwidth, which determines how fast symbols can be sent, and the number of signal levels for each symbol which determines how many bits can be sent during one signaling interval, to the maximum number of bits/second that can be sent.  The Shannon formula is for a channel with noise and combines the channel bandwidth and the signal-to-noise ratio to determine the maximum number of bits/second that can be sent over that channel. It does use signal level in the form of signal-to-noise ratio.  The Nyquist formula, as already noted, does not use signal level because it is immaterial as it assumes there is no noise.