Replace sensor with switch?

[Raymond Midge]

I removed an occupancy sensor from my ceiling, where it was the switch for the overhead exhaust fan...don't ask me how that came to be!

When I capped the wires and closed the breaker I was surprised that the lights and receptacles on the same circuit were still powered.
In this case, can I connect each black wire to the terminals of a single-pole switch?

Thanks for thinking about this.