Bypass capacitor vs low-pass filter
The trace from the power source to the capacitor has inherent parasitic inductance. This provides the series element to make a low-pass filter.

A more complete model of the circuit looks like this:







simulate this circuit &ndash; Schematic created using CircuitLab

I've drawn the load as a time-varying current source, because the main goal of the bypass capacitor is to reduce voltage variation due to changing current draw in the load. If/when you simulate your bypassing scheme, it's a good idea to use this model, and use the simulation to check if your bypass network presents a low impedance to the load at all frequencies it might excite with varying currents.